Network Working Group R. Gellens
Request for Comments: 2636 Qualcomm
Obsoletes: 2604 July 1999
Category: Informational
 Wireless Device Configuration (OTASP/OTAPA) via ACAP
Status of this Memo
 This memo provides information for the Internet community. It does
 not specify an Internet standard of any kind. Distribution of this
 memo is unlimited.
Copyright Notice
 Copyright (C) The Internet Society (1999). All Rights Reserved.
Abstract
 Wireless carriers today are faced with creating more efficient
 distribution channels, increasing customer satisfaction, while also
 improving margin and profitability. Industry trends are pushing the
 sale of handsets further into the retail channel. The cost and
 effort of provisioning handsets, activating users, and updating
 handset parameters can be greatly reduced by using over-the-air
 activation mechanisms. A comprehensive and extensible means for
 over-the-air provisioning and handset parameter updating is required.
 One approach is to purchase EIA/TIA/IS-683A (Over-the-air Service
 Provisioning of Mobile Stations in Spread Spectrum Systems)
 equipment. The cost of this has led carriers to seek alternative
 solutions. A very viable means for providing over-the-air (OTA)
 provisioning is to leverage the rollout of IS-707 data services
 equipment, which most carriers are in the process of deploying. This
 paper presents an approach to OTA provisioning that utilizes the
 deployment of IS-707 to deliver OTA provisioning and parameter
 upgrading.
 IS-707 data services makes available several methods of providing
 over-the-air provisioning and parameter updating. A well thought-out
 approach utilizing Internet-based open standard mechanisms can
 provide an extensible platform for further carrier service offerings,
 enhanced interoperability among back-end services, and vendor
 independence.
 This paper describes a viable and attractive means to provide
 OTASP/OTAPA via IS-707, using the ACAP [ACAP] protocol.
Table of Contents
 1. Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
 2. Feature Descriptions . . . . . . . . . . . . . . . . . . . 6
 2.1. OTASP Feature Description . . . . . . . . . . . . . . . 6
 2.2. OTAPA Feature Description . . . . . . . . . . . . . . . 6
 3. Operation . . . . . . . . . . . . . . . . . . . . . . . . . 7
 3.1. Initial Provisioning Activity . . . . . . . . . . . . . 7
 3.2. OTASP for Authorized Users . . . . . . . . . . . . . . . 8
 3.3. OTAPA Activity . . . . . . . . . . . . . . . . . . . . 8
 4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 9
 4.1. General Requirements . . . . . . . . . . . . . . . . . 9
 4.2. OTASP Requirements . . . . . . . . . . . . . . . . . . . 9
 4.3. OTAPA Requirements . . . . . . . . . . . . . . . . . . 10
 4.4. Provisioning Server Requirements . . . . . . . . . . . . 10
 4.5. Security Requirements . . . . . . . . . . . . . . . . . 11
 5. Architecture . . . . . . . . . . . . . . . . . . . . . . . . 11
 5.1. ACAP over TCP/IP . . . . . . . . . . . . . . . . . . . 11
 5.1.1. Mobile Authentication and A-Key Generation . . . . . 12
 5.1.2. Mobile Identification . . . . . . . . . . . . . . . 12
 5.1.3. ACAP Server . . . . . . . . . . . . . . . . . . . . 12
 5.1.4. Overview of ACAP Structure . . . . . . . . . . . . 13
 5.1.5. Data Organization and Capabilities . . . . . . . . . 13
 5.1.5.1. Structure . . . . . . . . . . . . . . . . . . . 14
 5.1.5.2. Conventions . . . . . . . . . . . . . . . . . . 15
 5.1.5.3. Dataset . . . . . . . . . . . . . . . . . . . . 15
 5.1.5.4. Entries and Attributes . . . . . . . . . . . . . 15
 5.1.5.5. NAM Records . . . . . . . . . . . . . . . . . . 16
 5.1.5.6. Server Roaming Lists . . . . . . . . . . . . . . 17
 5.1.5.7. Requested-Data Record . . . . . . . . . . . . . 18
 5.1.5.8. Sample Server Entry . . . . . . . . . . . . . . 18
 5.1.6. Administrative Client . . . . . . . . . . . . . . . 19
 5.1.7. Mobile Client . . . . . . . . . . . . . . . . . . . 20
 5.2. WAP with ACAP . . . . . . . . . . . . . . . . . . . . . 22
 5.3. Network-Resident vs. Configuration Data . . . . . . . . 23
 5.4. Intellectual Property Issues . . . . . . . . . . . . . 23
 6. Handset Protocol Suites . . . . . . . . . . . . . . . . . . 23
 6.1. ACAP over TCP/IP . . . . . . . . . . . . . . . . . . . 23
 7. IS-683A Compatibility . . . . . . . . . . . . . . . . . . . 24
 7.1. OTASP Operations . . . . . . . . . . . . . . . . . . . 24
 7.2. OTASP Call Flow . . . . . . . . . . . . . . . . . . . . 24
 7.3. OTAPA Operations . . . . . . . . . . . . . . . . . . . 24
 7.4. OTAPA Call Flow . . . . . . . . . . . . . . . . . . . . 25
 8. Alternative Methods . . . . . . . . . . . . . . . . . . . . 25
 8.1. IS-683A over TCP/IP . . . . . . . . . . . . . . . . . . 25
 8.1.1. OTAF Server . . . . . . . . . . . . . . . . . . . . 25
 8.1.2. Interface Application . . . . . . . . . . . . . . . 26
 8.1.3. Protocol Handset Suite . . . . . . . . . . . . . . 26
 8.2. Browser-Based Forms . . . . . . . . . . . . . . . . . . 26
 9. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . 27
 10. References . . . . . . . . . . . . . . . . . . . . . . . . 28
 11. Security Considerations . . . . . . . . . . . . . . . . . 28
 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . 28
 13. Author's Address . . . . . . . . . . . . . . . . . . . . 28
 14. Full Copyright Statement . . . . . . . . . . . . . . . . . 29
1. Terms
 Application Configuration Access Protocol (ACAP) -- An Internet
 protocol (RFC-2244) that provides remote storage and access of
 configuration and preference information.
 Activation -- A process in which a mobile station and network become
 programmed so that a mobile station becomes operable and can be used
 for cellular service once authorized by the service provider.
 Authentication -- A procedure used to validate a mobile station's
 identity.
 Authentication Center -- An entity that manages the authentication
 information related to the mobile station.
 Authentication Key (A-key) -- A secret 64-bit pattern stored in the
 mobile station. It is used to generate and update the mobile
 station's shared secret data. The A-key is used in the
 authentication process.
 Authorization -- An action by a service provider to make cellular
 service available to a subscriber.
 Call -- A temporary communication between telecommunications users
 for the purpose of exchanging information. A call includes the
 sequence of events that allocates and assigns resources and signaling
 channels required to establish a communications connection.
 Cellular Service Provider -- A licensee of the responsible government
 agency (in the U.S. a licensee of the Federal Communications
 Commission) authorized to provide Cellular Radiotelephone Service.
 Challenge/Response Authentication Mechanism using Message Digest 5
 (CRAM-MD5) -- An authentication mechanism which is easy to implement,
 and provides reasonable security against various attacks, including
 replay. Supported in a variety of Internet protocols. Specified as
 baseline mechanism in ACAP. CRAM-MD5 is published as RFC 2195.
 Code Division Multiple Access -- A technique for spread-spectrum
 multiple-access digital communications that creates channels through
 the use of unique code sequences.
 Customer Service Center -- An entity of a service provider that
 provides user support and assistance to subscribers.
 Customer Service Representative -- A person that operates from a
 customer service center and provides user support and assistance to
 subscribers.
 Diffie-Hellman Algorithm -- A public-key cryptography algorithm for
 exchanging secret keys. Uses the equation , where k is the secret
 key. The equation is executed by each party of the session based on
 the exchange of independently generated public values.
 Digits -- Digits consist of the decimal integers 0,1,2,3,4,5,6,7,8,
 and 9.
 Dual-mode Mobile Station -- A mobile station capable of both analog
 and digital operation.
 Electronic Serial Number (ESN) -- A 32-bit number assigned by the
 mobile station manufacturer used to identify a mobile station. The
 ESN is unique for each legitimate mobile station.
 Home Location Registry (HLR) -- The location register or database to
 which a MIN is assigned for record purposes such as subscriber
 information.
 Message Digest 5 (MD5) -- A one-way cryptographic hash function.
 Widely deployed in Internet protocols. Published as RFC 1321.
 Mobile Identification Number (MIN) -- The 10-digit number that
 represents a mobile station's directory number.
 Mobile Station (MS) -- A station, fixed or mobile, which serves as
 the end user's wireless communications link with the base station.
 Mobile stations include portable units (e.g., hand-held personal
 units) and units installed in vehicles.
 Mobile Switching Center (MSC) -- A configuration of equipment that
 provides cellular radiotelephone service.
 Mobile Terminal Authorizing System (MTAS) -- A control system that
 provides the capability to load the CDMA network HLR with mobile
 station profile information.
 Number Assignment Module (NAM) -- The mobile station's electronic
 memory module where the MIN and other subscriber-specific parameters
 are stored. Mobile stations that have multi-NAM features offer users
 the option of using their units in several different markets by
 registering with a local number in each location.
 Over-the-air Service Provisioning Function (OTAF) -- A configuration
 of network equipment that controls OTASP functionality and messaging
 protocol.
 Over-the-air Parameter Administration (OTAPA) -- Network initiated
 OTASP process of provisioning mobile station operational parameters
 over the air interface.
 Over-the-air Service Provisioning (OTASP) -- A process of
 provisioning mobile station operational parameters over the air
 interface.
 Quick-Net-Connect (QNC) -- An IS-707 data service capability that
 utilizes the Async Data Service Option number but bypasses the modem
 connection for a direct connection to an IP-based internet.
 Roamer -- A mobile station operating in a cellular system or network
 other than the one from which service was subscribed.
 Simple Authentication and Security Layer (SASL) -- An Internet
 protocol (RFC-2222) that provides a framework for negotiating
 authentication and encryption mechanisms.
 Service Provider -- A company, organization, business, etc. which
 sells, administers, maintains, and charges for the service. The
 service provider may or may not be the provider of the network.
 Shared Secret Data (SSD) -- A 128-bit pattern stored in the mobile
 station (in semi-permanent memory) and known by the network. The A-
 key is used to generate the SSD at the network and in the mobile
 station for comparison.
 Wireless Application Protocol (WAP) -- A set of network and
 application protocols including a datagram protocol (WDP), Transport
 Layer Security (WTLS), Transaction Protocol (WTP), Session Protocol
 (WSP), and Application Environment (WAE), which use carrier-based
 gateways to enable wireless devices to access Web resources. See
 <http://www.wapforum.org> for specifications and details.
2. Feature Descriptions
2.1. OTASP Feature Description
 The Over the Air Service Provisioning (OTASP) feature allows a
 potential wireless service subscriber to activate new wireless
 services, and allows an existing wireless subscriber to make
 services changes without the intervention of a third party. OTASP
 includes the following:
 * A way to establish a user profile.
 * "Over-The-Air" programming of a Number Assignment Module (NAM),
 IMSI and Roaming Lists, including Data option parameters, and
 optionally, service provider or manufacturer specific parameters
 (e.g., lock code, call timer).
 * An Authentication Key (A-key) Generation procedure.
 * A-key storage
2.2. OTAPA Feature Description
 The Over-the-Air Parameter Administration (OTAPA) feature allows
 wireless service providers to update a NAM, IMSI, and Roaming List
 information in the mobile station remotely without the intervention
 of a third party. This capability increases flexibility and reduces
 costs for carriers involved with mass changes that affect every
 handset, such as area-code splits.
 OTAPA includes the following:
 * Update a user's Number Assignment Module (NAM)
 * Update Data option parameters
 * Update service provider or manufacturer specific parameters (e.g.,
 Server address(es), lock code, call timer).
 * Update roaming lists
3. Operation
3.1. Initial Provisioning Activity
 A new subscriber needs to give the intended service provider
 sufficient information (e.g., name, address, etc.) to prove credit-
 worthiness and establish a record within the service provider's
 billing system. In addition, the ESN of the mobile station needs to
 be given to the provider. This may occur in three ways:
 Voice scenario -- A customer care representative collects credit
 information during a voice conversation. This call is made from a
 different phone (e.g., wired service) or is initiated using the IS-
 683A OTASP dialing scheme (i.e., *228xx).
 Once the user has been authorized, the customer care representative
 creates a record in the CDMA network HLR, thus allowing use of the
 CDMA network. In addition, a limited-time N-digit password is
 created which is tied to the ESN. The choice of N (how many digits)
 is up to the carrier (as a trade-off between security and user
 inconvenience). All required provisioning information (including
 the limited-time password) is loaded into the provisioning server.
 The user is then told to hang up and call a special number, of the
 form *228 XX <N-digit password> SEND (the XX code is the same as
 used in the initial voice call). This causes the mobile station to
 initiate a provisioning session.
 The mobile station and the provisioning server authenticate, and all
 required provisioning information is downloaded into the mobile
 station. The user receives some form of notification once the
 activity is complete. This notification can be an audible tone or a
 text message on the mobile station display. (The form and content of
 this notification can be part of the provisioning data downloaded by
 the mobile station.) Once this initial provisioning activity is
 complete the user has a fully authorized mobile station ready for
 use.
 Forms scenario -- An interactive user interface is presented via a
 browser on the mobile station. The subscriber fills in the
 requested information. (Note that entering non-numeric data presents
 some user interface challenges on many mobile devices.)
 A back-end server validates the information, and if possible, the
 customer is authorized, a limited-time password is generated, HLR
 and provisioning server records are created and the actual OTASP
 operation begins. Otherwise, a voice call is made to a customer
 care representative.
 Desktop scenario -- The subscriber uses a desktop (or in-store
 kiosk) web browser to contact the carrier, and enters the usual
 personal information.
 The carrier's server validates the information, and if possible, the
 customer is authorized, a limited-time password is generated, HLR
 and provisioning server records are created, and the subscriber is
 told to dial a special number on the handset. Once this code is
 entered, the actual OTASP operation begins. Otherwise, the user is
 asked to make a voice call to a customer care representative.
3.2. OTASP for Authorized Users
 Users already authorized for use of the CDMA network can also
 initiate provisioning activity. This could happen after being
 directed to do so by a Customer Care representative, either from a
 phone conversation or via mail notification. This type of OTASP
 activity is needed in cases where the carrier desires to upgrade
 CDMA parameters in the mobile stations or in cases where mobile
 station troubleshooting is needed.
 This type of OTASP occurs in similar fashion to the initial OTASP
 activity. The mobile station downloads the new provisioning
 information in the same way.
3.3 OTAPA Activity
 Typical OTAPA capability involves upgrading a large number of mobile
 stations. OTAPA activity needs to be performed in a manner that
 does not impose on revenue bearing CDMA network activity. OTAPA
 operations are initiated at the customer care center. This can be
 accomplished by queuing a notification to the mobile station (via
 1-way SMS or special caller-ID) after the provisioning server has
 the updated configuration data. OTAPA activity will not occur until
 the mobile station has acquired CDMA service on the carrier's
 network and the notification has reached the mobile station.
 Alternatively, OTAPA can be handled by including a recheck interval
 in the set of data used to provision the mobile station. When using
 a low-overhead protocol, such as ACAP [ACAP], it is reasonable to
 have a mobile station check in periodically to see if anything has
 changed. The time of day and/or day of week that such rechecks
 should occur could be included in the provisioning data.
 OTAPA activity can be terminated at any time due to user call
 activity.
4. Requirements
4.1. General Requirements
 IS-683A OTASP operations occur between a mobile station and an
 over-the-air service provisioning function (OTAF) using IS-95A
 traffic channel data burst messages. OTASP/OTAPA via data services
 require that the CDMA carrier have an IS-707 data services capable
 network. The IS-707 service must be either Packet Data Service
 (IS-707.5) or Quick-Net-Connect (QNC).
 The mobile station must support:
 * IS-707 Data Service capability
 * Packet/QNC RLP protocol
 * PPP protocol to peer to the IS-707 IWF
 * IP protocol to provide the network layer for routing to the
 provisioning server
 * A transport layer for end-to-end communication (such as TCP)
 * Authentication and optionally encryption
 * Application software to handle the provisioning protocol and
 memory access.
 * Domain Name System (DNS) query capabilities sufficient to obtain
 the (IP) address of the provisioning server (or the provisioning
 server's address could be provided during PPP negotiation).
 Lastly, the ability must exist for the mobile to make a data call
 (optionally) a voice call without a MIN.
4.2. OTASP Requirements
 The OTASP function requires the mobile station to originate an IS-
 707 data call and (optionally) a voice call using a completely
 unprovisioned mobile station. The CDMA network must support this
 capability.
 OTASP via data services uses a provisioning server that contains the
 parameter information for mobile stations. The authorizing agent
 (or software) at the customer care center must be able to add user
 and mobile station information into both the CDMA network HLR and
 the provisioning server during the initial authorizing process. The
 provisioning server must be capable of servicing a mobile as soon as
 its record is created.
4.3. OTAPA Requirements
 IS-683A OTAPA is performed by a mobile-terminated call that
 downloads parameters to the mobile station. OTAPA calls occur
 without user interaction.
 In order to perform OTAPA via data services the network needs to
 direct the mobile station to initiate a special-purpose data call.
 Several existing methods can be used to implement this capability,
 for example, a mobile-terminated one-way SMS message. The SMS
 message content can contain any information required by the mobile
 station. The mobile station would need a simple parser of SMS
 messages in order to know when to originate an OTAPA call, as
 opposed to normal SMS message processing. The OTAPA call would be
 performed in similar fashion to a registration call. More
 specifically, the user would not be informed of the call activity.
 There are alternative means that can be employed to initiate OTAPA
 activity; for example, a mobile-terminated voice call with caller-ID
 using a specialized telephone number. Another alternative is for
 mobile stations to periodically check in with the provisioning
 server to check for updated information. ACAP, for example, is
 designed for such a model. The recheck interval, as well as the
 time of day and/or day of week that such checks should be used, can
 be part of the provisioning data sent to the mobile stations.
4.4. Provisioning Server Requirements
 IS-683A utilizes an over-the-air service provisioning function
 (OTAF) to perform the network-side provisioning activity.
 OTASP/OTAPA via data services replaces the OTAF with a provisioning
 server. The provisioning server resides on an IP network within the
 controlled confines of the carrier. The provisioning server must
 perform all the service provisioning and parameter administration
 functions that the OTAF provides. The provisioning server must also
 have an interface to the carrier's Mobile Terminal Authorizing
 System (MTAS). This interface serves to synchronize the
 provisioning server with the information in the MTAS. The specific
 requirements of this interface depend on the capabilities and
 interfaces of the carrier's customer care center system(s). The
 provisioning server must be capable of receiving dynamic updates
 from the MTAS and have the provisioning information immediately
 available for downloading into the chosen mobile station. A
 standard ACAP server provides an excellent means to meet these
 requirements.
 The provisioning server must be capable of performing an
 authentication procedure with the mobile station. This
 authentication mechanism must be capable of authenticating both the
 mobile station and the provisioning server.
4.5. Security Requirements
 OTASP requires that an authentication procedure be performed to
 validate the mobile station to the provisioning server, while OTAPA
 requires a mechanism where the mobile validates the server.
 The provisioning server must be capable of either:
 * OTAF A-key generation using a Diffie-Hellman mechanism
 Or:
 * Receiving A-keys from the carrier network.
 Since data OTASP/OTAPA operates over IP within the carrier's
 network, end-to-end encryption between the mobile station and the
 provisioning server should be considered as a future enhancement.
 End-to-end encryption protects against attacks from within a
 carrier's network, and safeguards the provisioning data (for
 example, roaming lists).
5. Architecture
5.1. ACAP over TCP/IP
 Figure 1 shows a provisioning server in the carrier's intranet which
 supports the Application Configuration Access Protocol (ACAP, RFC
 2244). An administrative client in the customer care domain updates
 this server using ACAP. Handsets are provisioned and configured
 using a small ACAP client.
 [Figure 1 -- see PostScript version]
 ACAP is an open Internet protocol designed to solve the problem of
 client access to configuration and related data. Among its primary
 goals are protocol simplicity, support for thin clients, and ease of
 operation over limited bandwidth. ACAP provides a high degree of
 extensibility, especially in authentication mechanisms, specialized
 attribute handling, and data management.
5.1.1. Mobile Authentication and A-Key Generation
 The mobile client authenticates with the ACAP server prior to
 performing any activities. Authentication uses the mobile's ESN and
 a shared secret. Provisioned mobiles derive the shared secret from
 the A-Key; unprovisioned mobiles use a limited-time password as the
 secret.
 The limited-time password is provided to the user by the Customer
 Care representative during the initial call (as instructions to dial
 a specific number). This code is N digits long. The carrier
 selects the number of digits, as a trade-off between security and
 user convenience.
 The baseline ACAP authentication mechanism uses the shared secret
 plus a random challenge from the server as input to a one-way
 cryptographic hash function (specifically, keyed-MD5). This is
 analogous to the existing IS-683A authentication mechanism which
 uses a random challenge and the CAVE algorithm.
 An A-Key is generated using a Diffie-Hellman exchange, as is done in
 IS-683A.
5.1.2. Mobile Identification
 Provisioning records are identified using the ESN and the current
 NAM in use.
5.1.3. ACAP Server
 As a standard ACAP server, the provisioning server includes
 configurable datasets and dataset inheritance for the management of
 the data stores.
 The administrative client can use the same simple ACAP protocol to
 load and modify the ACAP server as the mobile stations uses for
 provisioning. While any implementation-specific mechanisms
 available from the server vendor could instead be used for this
 purpose, the ability to use ACAP can greatly simplify the
 administrative client, as well as make it independent of the server.
 ACAP includes an authentication framework (Simple Authentication and
 Security Layer, SASL, RFC 2222)[SASL]. SASL allows any standard or
 custom authentication and encryption mechanism to be used. One of
 the most important features of SASL is that it is designed for a
 world in which what is "good enough" security today isn't good
 enough tomorrow. As the threat model changes, SASL allows higher-
 strength mechanisms to be easily added while supporting already
 deployed clients and servers. SASL is achieving widespread
 deployment in a number of Internet protocols.
 Strongpoints: Since the ACAP protocol was designed for precisely
 this type of provisioning activity, its adoption can greatly reduce
 the cost, time to market, and support required for the provisioning
 server. Additionally, the ACAP protocol provides an open standard
 method for mobile stations and other systems to access the
 provisioning server. Commercial ACAP servers are being developed by
 numerous companies. The ACAP client code is very small and simple,
 and thus can be incorporated into virtually any mobile device at
 minimal cost. As an open standard, the ACAP protocol has benefited
 from years of review and experience.
5.1.4. Overview of ACAP Structure
 ACAP organizes data by datasets. The structure of a dataset is
 defined by the dataset class. Generally, ACAP servers do not have
 knowledge of dataset classes. This allows the dataset to be
 expanded without modifying the server in any way. A dataset is an
 instantiation of the dataset class, which is a logical definition of
 what is in a dataset, and how it is used.
 Datasets contain entries. Entries contain attributes and values.
 Attributes and values are actually metadata, such as name, length,
 and value. Any entry can also be a dataset (datasets are
 hierarchical).
 For example, consider the ACAP addressbook dataset class, designed
 to hold names, email addresses, phone numbers, and related
 information for a person's contacts. A given user may have one or
 more addressbook datasets. Each entry holds information about one
 person or entity. Attributes in the entry hold specific items of
 information, such as the given name, surname, various email
 addresses, phone numbers, and so forth. If an entry is a list of
 people (such as a mailing list or specific group of people), it is a
 subdataset, containing its own entries. Some clients may look at
 only a subset of the attributes. For example, a mobile handset ACAP
 client may download only the alias (nickname), name, primary phone
 number and email address of each entry, while a desktop client may
 access all attributes.
5.1.5. Data Organization and Capabilities
 ACAP provides custom hierarchical datasets. Server data can be
 organized to fit the needs of the applications using the dataset.
 In OTASP/OTAPA over ACAP, data on the server is organized to both
 take advantage of ACAP capabilities and to use items that are
 identical to IS-683A, allowing for reuse of IS-683A handset engines.
 ACAP servers also support data inheritance. All data items which
 are physically in the inherited dataset and not in the inheriting
 dataset logically also exist in the inheriting dataset. This is
 recursive, as the inherited dataset can itself inherit from another
 dataset. This powerful concept allows potentially large groups of
 mobile stations to inherit items from a single common entity. For
 example, preferred roaming lists can be stored in datasets based on
 geographic areas, and automatically inherited by an individual
 mobile station in that area. The roaming lists could be further
 subdivided, for example based on tiers of free NVRAM in the mobile.
 The mobile client need not be aware of this; it happens entirely on
 the server.
 ACAP uses trees to provide the data hierarchy. These data trees can
 be viewed as similar to the directory/file structure used with all
 common operating systems. The built-in inheritance mechanism,
 together with the hierarchical structure, makes it extremely easy to
 update general data without disturbing specific data.
 Datasets exist within the user, group, and host hierarchies. The
 user hierarchy holds datasets which belong to individual users. The
 group hierarchy holds datasets which belong to groups (for example,
 the "Region." groups in section 5.1.6.3 Server Roaming Lists). The
 host hierarchy holds datasets which are for specific machines or
 systems.
 In addition to providing customizable data trees, ACAP also provides
 several standard datasets for all clients. There is a capabilities
 dataset that contains information on custom functionality and
 enhanced features available to a specific client or at the site
 generally. This allows a server to advertise any protocol
 extensions, specialized attribute handling, or other enhanced
 functionality it supports. A client that needs to use these
 features can thus easily determine what is available before trying
 to use them.
5.1.5.1. Structure
 We divide the data accessed by the client into provisioning items,
 group items, and client state items. Provisioning data contains NAM
 items and requested-data items. Group items (such as preferred
 roaming lists), are not specific to any mobile device. Group items
 physically exist in their own datasets, but through inheritance
 logically appear in client datasets.
 The mobile stations always read data from provisioning entries and
 write data to client state entries. This structure makes both
 mobile clients and server configuration easy and simple, while
 allowing for extensive custom and diagnostic capabilities.
5.1.5.2. Conventions
 "" This signifies the empty string (used here for ACAP entries).
 ~ This is shorthand for "user/<userid>". It is part of the ACAP
 protocol.
5.1.5.3. Dataset
 Provisioning information is located in the "OTAP" dataset class.
 (The full specification of this dataset will be published in a
 subsequent document.) The prefix "Provision." is used for items that
 are to be downloaded to the mobile, and the prefix "Client." is used
 for items which the client stores on the server.
 Provisioning data within the OTAP dataset is organized as a series
 of items, each of which is stored in its own entry. The entry name
 is the item name, and the "OTAP.VALUE" attribute contains the item
 value. This structure permits change notification on a per-item
 basis.
 We chose the "Provision" and "Client" names to simplify various
 operations. For example, the mobile client can easily download all
 changed provisioning items by performing a search which returns the
 "OTAP.VALUE" attribute of all entries whose name begins with
 "Provision" and whose modtime is greater than the last time the
 client retrieved data. An administrative client can easily generate
 a report of all clients which have not received the most recent
 update by searching for all entries named "Client" whose
 "OTAP.modtime" attribute is less than the desired value.
 A partial list of items follows.
5.1.5.4. Entries and Attributes
 dataset.inherit
 This is a standard ACAP attribute that identifies the location of
 inherited data. It exists in the "" entry (the entry with the empty
 name) within each dataset.
5.1.5.5. NAM Records
 The OTAP dataset class contains an entry for each provisioned
 mobile. The standard location for provisioning records is:
 /OTAP/USER/<esn>/<nam>/
 This tree format allows multiple NAMs per ESN. The specific entries
 contain data in IS-683A parameter block types.
 For example, the CDMA NAM would be stored in an entry called:
 /OTAP/USER/<esn>/<nam>/Provision.CDMA-NAM/
 The entries below show how NAM records would be organized on the
 ACAP server:
 CDMA/Analog NAM
 Entry-Path: /OTAP/USER/<esn>/<nam>/Provision.CDMA-AMPS-NAM/
 OTAP.Value: {17} xx xx xx ... xx
 The CDMA/Analog NAM entry from IS-683A (section 4.5.2.1)
 consists of at least 129 information bits, depending on the
 number of SID NID list entries. This is stored as 17 (or more)
 octets of binary data (padding is used to ensure an integral
 number of octets).
 Mobile Directory Number
 Entry-Path: /OTAP/USER/<esn>/<nam>/Provision.MOBILE-DN/
 OTAP.Value: {10} nnnnnnnnnn
 The Mobile Directory Number from IS-683A contains BCD-encoded
 digits representing the phone number. This is stored as a
 string of 10 or more ASCII digits, e.g., "6195551212".
 CDMA NAM
 Entry-Path: /OTAP/USER/<esn>/<nam>/ Provision.CDMA-NAM/
 OTAP.Value: {13} xx xx xx ... xx
 The CDMA-NAM entry from IS-683A (section 4.5.2.3) consists of at
 least 100 information bits, depending on the number of SID-NID
 list entries. This is stored as 13 (or more) octets of binary
 data (padding is used to ensure an integral number of octets).
 IMSI_T
 Entry-Path: /OTAP/USER/<esn>/<nam>/ Provision.IMSI_T/
 OTAP.Value: {7} xx xx xx xx xx xx xx
 The IMSI_T entry from IS-683A (section 4.5.2.4) consists of 55
 bits of information in five fields. This is stored left-
 justified in 7 octets of binary data.
5.1.5.6. Server Roaming Lists
 The ACAP Server will have an entry for each different roaming list
 configuration for a carrier. The example below assumes that the
 desired differentiation for the roaming list is geographic, with
 subdivisions for tiers of mobile free NVRAM It shows that for each
 region there exists a set of roaming lists per free NVRAM range.
 Note that a carrier can easily implement different or further
 differentiation (e.g., by phone vendor or product type) by simply
 changing the dataset tree and assigned the appropriate value to the
 "dataset.inherit" attribute in the provisioning records.
 /OTAP/GROUP/region.NorthEast/free-nv.128-512/
 preferred.roaming.list/OTAP.Value
 /OTAP/GROUP/region.NorthEast/free-nv.512-1024/
 preferred.roaming.list/OTAP.Value
 /OTAP/GROUP/region.SouthEast/free-nv.128-512/
 preferred.roaming.list/OTAP.Value
 /OTAP/GROUP/region.SouthEast/free-nv.512-1024/
 preferred.roaming.list/OTAP.Value
 /OTAP/GROUP/region.NorthWest/free-nv.128-512/
 preferred.roaming.list/OTAP.Value
 /OTAP/GROUP/region.NorthWest/free-nv.512-1024/
 preferred.roaming.list/OTAP.Value
 /OTAP/GROUP/region.SouthWest/free-nv.128-512/
 preferred.roaming.list/OTAP.Value
 /OTAP/GROUP/region.SouthWest/free-nv.512-1024/
 preferred.roaming.list/OTAP.Value
5.1.5.7. Requested-Data Record
 Inside the OTAP dataset is an entry with the name
 "Provision.Requested-Data", which contains one attribute called
 "OTAP.Requested-Data". This attribute is multi-valued. It is
 either NIL or contains a list of strings. Each string is the name
 of one element of data that the server requests the client to
 supply.
 After authenticating, the ACAP client issues a SEARCH command to
 retrieve the values of the "OTAP.Requested-Data" attribute of the
 "Provision.Requested-Data" entry. The client processes the returned
 values (if any) by issuing a STORE command to set one or more
 attributes in the "Client" entry. The value of each attribute is
 either the corresponding mobile value (which may be an empty string
 if the item has no value), or the special value "[N/A]" if the item
 does not exist or is unknown on the mobile.
 This mechanism is quite general, and can be used in the normal OTASP
 case to modify the mobile's dataset as appropriate for the condition
 of the mobile. For example, the inheritance could be set based on
 the amount of NVRAM available, to cause one set of preferred roaming
 list data or another to be used. This mechanism can also be used in
 other situations, such as to retrieve a complete set of mobile
 configuration parameters for diagnostic reasons.
5.1.5.8. Sample Server Entry
 The entry below is an excerpt of a sample ACAP server dataset entry
 for a single mobile station, with an ESN of FB9876E and using NAM 1:
 /OTAP/USER/FB9876E/1/
 entry = ""
 dataset.inherit = "/OTAP/GROUP/region.NorthEast/
 free-nv.128-512/preferred.roaming.list/
 OTAP.Value/"
 entry = "Provision.Requested-Data"
 OTAP.Requested-Data = ("Phone-Make" "Phone-Model" "SW-Rev"
 "Free-NVRAM")
 entry = "Client"
 OTAP.Phone-Make = "Qualcomm"
 OTAP.Phone-Model = "pdQ1900"
 OTAP.SW-Rev = "001.030.0908"
 OTAP.Free-NVRAM = "65536"
 OTAP.Last-Modtime = "199812181703"
 entry = "Provision.Mobile-DN"
 OTAP.Value = {10} 619 555 1234
 entry = "Provision.CDMA-NAM"
 OTAP.Value = {13} xx xx xx xx xx xx xx xx xx xx xx
 xx xx
 This dataset shows not only provisioning data which was downloaded
 into the mobile station, but also the items of client data requested
 by the server (the Requested-Data attribute) and the values of those
 items (the "Client" entry). It also indicates that the mobile
 client successfully stored the values associated with the modtime
 "199812181703". In addition, it shows that this client inherits
 data (i.e., roaming lists) from the "NorthEast" region.
5.1.6. Administrative Client
 The administrative client loads initial provisioning information
 into the server, including specifying the roaming list to inherit.
 The administrative client also updates provisioning server records
 as needed, and retrieves data for reports (such as a list of clients
 which have not yet been updated).
 Data is loaded into provisioning records by using the ACAP STORE
 command. The administrative client authenticates to the ACAP server
 using credentials that permit access to datasets for mobiles.
 When a new mobile is authorized for service, the administrative
 client creates the dataset by storing into it values that are
 specific for the device. It also sets the "dataset.inherit"
 attribute so that values which are not tied to the specific mobile
 are inherited as appropriate.
 * Updates to user records
 Existing user records may need updating from time to time. For
 example, a user may change service plans or purchase an
 additional or replacement mobile device, or the carrier may
 need to modify some aspect of provisioned data.
 * Perusal and editing of provisioning records
 The administrative client can provide general browse and edit
 capability for user records.
 * Report generation
 The administrative client can extract data from the ACAP server
 in order to generate reports. For example, after OTAPA
 activity, a carrier may wish to identify those mobiles which
 have not yet been updated.
 * Queuing of OTAPA sessions
 Depending on the OTAPA update procedures chosen (e.g., SMS,
 CLID, periodic recheck), the administrative client may be
 involved in initiating the activity. This may or may not use
 an interface to the provisioning server.
5.1.7. Mobile Client
 The ACAP mobile client is implemented as a state machine that
 performs the equivalent of IS-683A provisioning parameter
 information exchange and non-volatile memory storage. The ACAP
 Client state machine diagram (Figure 2) and descriptions are below.
 [Figure 2 -- see PostScript version]
 * Establish Transport Layer/Authenticate
 Authentication and/or encryption can occur at the application
 layer and/or at the network/transport layer.
 Basic ACAP authentication occurs in the application layer
 (i.e., within the ACAP session), and in its baseline form uses
 the CRAM-MD5[CRAM-MD5] mechanism. If desired, other mechanisms
 can be used which provide more protection and encryption. This
 occurs after the transport layer is established, as shown in
 the client state machine diagram above
 Figure 3 shows the CRAM-MD5 authentication mechanism for an
 unprovisioned mobile. In the case of provisioned mobiles, the
 shared secret is derived from the A-Key, instead of the
 limited-time N-digit code used for unprovisioned devices.
 Use of basic ACAP authentication is preferred for initial
 implementations of data-OTASP because it is simple, easy to
 implement, and all procedures and methods are in place.
 Stronger SASL mechanisms and/or IPSec can be rolled out in the
 future without disrupting the deployed base.
 [Figure 3 -- see PostScript version]
 * Requested-data SEARCH
 The mobile ACAP client issues a search command asking the
 server to return the attribute "OTAP.Requested-Data" in the
 entry "Requested-Data".
 * Receive requested-data values
 The server instructs the client to store attributes by
 returning one or more values of requested-data in response to
 the Requested-Data SEARCH.
 For example, the attribute "OTAP.Requested-Data" in the entry
 "Requested-Data" might contain four values: "phone-make",
 "phone-model", "SW-Rev", and "Free-NVRAM".
 * STORE attribute list
 If the response to the requested-data SEARCH returns any
 values, the client issues a STORE command. Each attribute in
 the STORE command corresponds to one item of requested-data.
 If the client does not recognize an item, it stores the string
 "[n/a]".
 Continuing with our example, the client uses this STORE command
 to write four attributes into the "Client" entry. Each
 attribute name is identical to one value of the
 OTAP.Requested-Data" attribute (with the prefix "OTAP." added).
 Each attribute value is determined by the respective mobile
 value.
 In our example, this STORE command sets the following
 attributes and values:
 - "OTAP.Phone-Make" = "Qualcomm
 - "OTAP.Phone-Model" = "pdQ1900
 - "OTAP.SW-Rev" = "001.030.0908"
 - "OTAP.Free-NVRAM" = "65536"
 * Provisioning data SEARCH
 The mobile ACAP client issues a search command to retrieve any
 items of provisioning data that have changed since it last
 checked in (which in the initial session retrieves all
 provisioning data).
 This SEARCH command asks the server to return the "OTAP.Value"
 attribute of any entries whose name starts with "provision."
 (case-insensitive) and whose modtime is greater than the
 supplied value (which is zero for an unprovisioned mobile).
 * Receive provisioning data and modtime
 The server returns the provisioning items, each as one entry
 name and one attribute value. The server response to the
 SEARCH command includes the modtime of the latest entry
 returned.
 * Save values
 The mobile writes the returned values into NVRAM.
 * STORE modtime
 The ACAP client stores the returned modtime on the server as an
 acknowledgement that the data was received and NVRAM updated.
 * LOGOUT
 The client issues the LOGOUT command.
 * Close transport layer
 The client closes the TCP connection.
 * End call
 The data call is terminated.
5.2. WAP with ACAP
 An advantage of the ACAP solution is that is can easily coexist with
 a WAP-based mechanism, giving carriers more options.
 A carrier can deploy handsets into its service area which use WAP-
 based provisioning, if desired, alongside those which use ACAP
 provisioning. All that is required is that the WAP server contain a
 small ACAP client (or an interface to an ACAP server).
 Figure 4 shows how mobile stations can be configured using a WAP
 browser. By using an ACAP server for provisioning, carriers are
 free to simultaneously deploy mobile stations that use either WAP or
 ACAP, as desired. In either case, the ACAP server is the source for
 provisioning data.
 [Figure 4 -- see PostScript version]
5.3. Network-Resident vs. Configuration Data
 It is useful to recognize that wireless devices access two different
 types of carrier-provided data: network-resident and configuration.
 Network-resident data exists primarily within the carrier's network.
 Examples include account status, billing detail, service plan
 options, etc. While mobiles may access this information for user
 display, it resides in the network. Configuration data, in
 contrast, affects the operation of the handset, is usually not shown
 to the user, and must persist in the device.
 For network-resident data access, the obvious choice is the web.
 The data is highly interactive and time-variant, making web browsers
 a reasonable solution. Any appropriate web browser can be used.
 There are many good reasons for having a web browser in a wireless
 device which contains a display and is capable of user interaction.
 For configuration data, the best solution is to use ACAP. ACAP is
 optimized for the job, can be implemented quickly, requires a very
 small amount of memory, and does not depend on a display or any user
 interaction capability.
 Trying to use the same access method for both types of data
 unnecessarily complicates the solution, leading to increased design,
 development, and debug time and expense. It makes it more difficult
 to offer low-cost devices. Since the two types of data
 fundamentally differ, it is good engineering practice to select
 optimal code and protocols for each.
5.4. Intellectual Property Issues
 There are no known intellectual property issues with the ACAP
 solution. The ACAP specification was developed within the IETF, and
 no ownership, patent, or other IP claims have been asserted.
 Multiple independent vendors are developing ACAP clients and
 servers, in addition to the existing usage in deployed products.
6. Handset Protocol Suites
6.1. ACAP over TCP/IP
 Figure 5 depicts the mobile station protocol suite for the ACAP over
 TCP/IP solution. The mobile station is capable of supporting both
 IS-683A OTASP and OTASP over ACAP.
 [Figure 5 -- see PostScript version]
7. IS-683A Compatibility
7.1. OTASP Operations
 To maximize compatibility and allow for reuse of IS-683A handset
 code, the data formats used in OTASP over ACAP are identical to
 those used in IS-683A. Section 5.1.5 Data Organization and
 Capabilities discusses this in more detail.
 OTASP via IS-683A requires custom design and development for the
 specific CDMA infrastructure used by a carrier. This can greatly
 limit the data management capabilities and significantly reduces the
 extensibility of the solution. Conversely, OTASP over data can be
 implemented on a generic IP network using an Internet standards-
 based capability that provides extensible provisioning activities
 for carriers.
 OTASP over data uses a traffic channel whereas IS-683A OTASP runs
 over the limited-bandwidth signaling channel.
 IS-683A OTASP operations are inherently simultaneous voice and data.
 This allows the customer care representative to extract information
 from the mobile station while conversing with the user. OTASP over
 data services is a data-only solution (at least for now). This
 makes OTASP operations slightly more sequential and potentially
 problematic. Simultaneous voice and data will alleviate this issue.
7.2 OTASP Call Flow
 The call flow diagram (Figure 6) depicts the message sequence and
 operations for a typical IS-683A OTASP (provisioning) call. Any
 data-OTASP solution must perform all the functions of the IS-683A
 OTASP call. The proposed solution meets these requirements.
 [Figure 6 -- see PostScript version]
7.3. OTAPA Operations
 Data-OTAPA requires the ability to instruct mobiles to originate a
 data call to the provisioning server. Several viable approaches are
 discussed in sections 3.3 OTAPA Activity and 4.3 OTAPA
 Requirements.
 OTAPA over data has the potential to require far less channel
 resources to download new information to mobile stations. The ACAP
 server inherently only communicates changes to the clients, thus
 only changed information needs to be downloaded to the mobile
 stations using OTAPA over data via ACAP.
7.4. OTAPA Call Flow
 The call flow diagram (Figure 7) depicts the message sequence for a
 typical IS-683A OTAPA operation. Any data-OTAPA solution must
 perform all the functions of the IS-683A OTAPA call. The proposed
 solution meets these requirements.
 [Figure 7 -- see PostScript version]
8. Alternative Methods
8.1. IS-683A over TCP/IP
 One alternative is to port IS-683A to TCP, remaining as close as
 possible to the IS-683A protocol exchange.
 Figure 8 depicts the architecture and communications backbone to
 support OTASP/OTAPA via IS-707 data services with a provisioning
 server based on the IS-683A OTAF function.
 [Figure 8 -- see PostScript version]
8.1.1. OTAF Server
 This provisioning server is modeled after the IS-683A OTAF. The
 OTAF server performs the specific operations and messaging of IS-
 683A OTAF. This includes A-key reauthentication procedures.
 Strongpoints:
 (1) OTAF and mobile station behavior mirrors IS-683A (reduced
 duplicate software in mobile station). Nearly all procedures fully
 defined.
 Drawbacks:
 (1) The OTAF server would need to be custom-designed and built.
 (2) No inherent data manipulation capabilities in the OTAF server.
 All required or desired data management activities would have to be
 built from scratch.
 (3) Interface application would require a non-standard interface
 (and therefore proprietary) to OTAF server.
 (4) End-to-end encryption scheme still needed for full security.
8.1.2. Interface Application
 This function loads all required provisioning-related information
 from the CDMA network information system to the OTAF server. This
 includes the queuing of provisioning transactions and data.
8.1.3. Protocol Handset Suite
 Figure 9 depicts the mobile station protocol suite for the IS-683A
 over TCP/IP solution. The OTASP client is capable of supporting
 both IS-683A OTASP activities or OTASP activities over the data
 transport.
 [Figure 9 -- see PostScript version]
8.2. Browser-Based Forms
 Another alternative is to use forms embedded in web pages.
 Encapsulating the provisioning data into custom tags embedded in a
 web form is an idea that at first seems attractive. There are a lot
 of advantages in having a browser in the handset, web servers are
 very widely deployed, and everyone is familiar on some level with
 the web.
 However, a meta-protocol for this would need to be designed, and a
 fully detailed specification produced. This solution requires
 custom software on the provider side to handle the meta-protocol.
 It additionally requires handset vendors to add custom software in
 the handset browser to handle this protocol.
 This solution would require a provisioning-capable browser in every
 phone. While it may be desirable to have a browser, the decision to
 require it needs to be considered carefully, especially in light of
 the memory requirements it would impose on all devices.
 This solution would complicate the handset browser, by requiring it
 to handle provisioning as well as browsing. As provisioning and
 browsing are functionally dissimilar, this code is not a natural fit
 within the browser. Implementing this solution would require a
 significant increase in development and debug resources, and thus
 negatively impact time-to-market and cost.
 Also because the web is functionally dissimilar, a high level of
 carrier-side customization would be needed, leading to reduced
 vendor choice and increased deployment costs.
 This approach would layer custom data on top of a standard protocol.
 This would require design work, and would not have much time for
 open review before deployment, greatly increasing the risk. By
 contrast, ACAP has had years of open review and refinement.
 This approach also limits the extensibility of the solution. ACAP,
 conversely, is very extensible. Because ACAP is such a simple
 protocol, it can be added to a wide variety of applications at low
 cost. This allows increasing numbers of applications on the mobile
 device to share information with servers as well as desktop
 applications.
9. Conclusion
 ACAP provides a high degree of extensibility, especially in
 authentication mechanisms, custom attribute handling, and data
 management. By using an Internet standard protocol,
 interoperability and integration with a variety of equipment is
 possible, and carriers are not locked into any vendor. It is also
 easier to add new levels of service and capabilities, especially
 integration with future subscriber devices and applications (e.g.,
 email).
 Since an ACAP client is so small, it can be incorporated into
 virtually any device, even low-end ones without displays, and can be
 added without sacrificing other features. The simplicity of the
 client and protocol directly translate to shorter development cycles
 and faster time-to-market.
 Because the ACAP protocol was designed for precisely this type of
 provisioning activity, its adoption can greatly reduce the cost,
 time to market, and support required for the provisioning server as
 well as the handsets. As an open standard, the ACAP protocol has
 benefited from years of review and experience.
 Another advantage of the ACAP solution is that is can easily coexist
 with a WAP-based mechanism, giving carriers more options and
 reducing the minimal requirement burden on mobile devices.
 A carrier can deploy handsets into its service area which use WAP-
 based provisioning, if desired, alongside those which use ACAP
 provisioning. By using an ACAP server for provisioning, carriers
 are free to simultaneously deploy mobile stations that use either
 WAP or ACAP, as desired.
 The lack of intellectual-property issues further adds to ACAP's
 appeal.
10. References
 [ACAP] Newman, C. and J. Myers, "ACAP -- Application
 Configuration Access Protocol", RFC 2244, November 1997.
 [CRAM-MD5] Klensin, J., Catoe, R. and P. Krumviede, "IMAP/POP
 AUTHorize Extension for Simple Challenge/Response", RFC
 2195, September 1997.
 [SASL] Myers, J., "Simple Authentication and Security Layer
 (SASL)", RFC 2222, October 1997.
11. Security Considerations
 Security is discussed in many sections of this document. In
 particular, the need and methods to guard against unauthorized
 updating of handsets, usurpation of newly-created accounts,
 compromise of handset security values, and disclosure of carrier
 proprietary data and handset parameters is covered.
12. Acknowledgments
 Jim Willkie and Marc Phillips contributed greatly to this document.
 Their help is very much appreciated.
13. Author's Address
 Randall Gellens
 QUALCOMM Incorporated
 6455 Lusk Boulevard
 San Diego, CA 92121-2779
 Phone: +1 619 651 5115
 EMail: randy@qualcomm.com
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