1. 1 Lucent Technologies grants a free, irrevocable license to 3GPP2 and its Organizational Partners to incorporate text or other copyrightable material contained in the contribution and any modifications thereof in the creation of 3GPP2 publications; to copyright and sell in Organizational Partner's name any Organizational Partner's standards publication even though it may include all or portions of this contribution; and at the Organizational Partner's sole discretion to permit others to reproduce in whole or in part such contribution or the resulting Organizational Partner's standards publication. Lucent Technologies is also willing to grant licenses under such contributor copyrights to third parties on reasonable, non-discriminatory terms and conditions for purpose of practicing an Organizational Partner’s standard which incorporates this contribution. This document has been prepared by Lucent Technologies to assist the development of specifications by 3GPP2. It is proposed to the Committee as a basis for discussion and is not to be construed as a binding proposal on Lucent Technologies. Lucent Technologies specifically reserves the right to amend or modify the material contained herein and to any intellectual property of Lucent Technologies other than provided in the copyright statement above. TSG-X MMD TITLE: Review of Proposals for Handoff from VoIP on HRPD to 1X Circuit voice SOURCE: Mike Dolan mfdolan@lucent.com Tom Towle ttowle@lucent.commfdolan@lucent.comttowle@lucent.com Nancy Lee nylee@lucent.comnylee@lucent.com ABSTRACT: This contribution provides an analysis of the two major approaches to Handoff from VoIP on HRPD to 1X circuit voice, (1) ANSI-41 based and (2) IMS/MMD based. RECOMMENDATION: For discussion. 3GPP2 X32-20050620-xxx

2. 2 Major Proposals for HO to 1X: Lucent: IMS/MMD based Model Motorola: Handoff via ANSI-41 Model Nortel: IMS/MMD based Model Qualcomm: Handoff via ANSI-41 Model

3. 3 Generic ANSI-41 Handoff Model 1X BSC Anchor MSC MS 2nd MSC 1X BSC 3rd MSC 1X BSC ANSI-41 Signaling Dedicated Handoff Trunk Group(s)

4. 4 Details on Generic ANSI-41 Handoff  Initial MSC is the “Anchor MSC” and is responsible for feature handling and handoffs to other MSCs. –Feature delivery. –SMS delivery. –Etc.  Dedicated handoff trunk groups are required between the Anchor MSC and any other MSC that a call might be handed off to.

5. 5 ANSI-41 Based Handoff: HRPD to 1X Circuit HRPD (DO) AN (New) Handoff Function (Anchor MSC) MS MSC 1X BSC MSC 1X BSC MGWMGCF New Signaling Interface SIP New ANSI-41 Signaling New Dedicated Handoff Trunk Group(s) IMS Existing ANSI-41 Signaling Existing Dedicated Handoff Trunk Group(s)

6. 6 IMS/MMD Based Handoff: HRPD to 1X Circuit HRPD (DO) AN MS Anchor MSC 1X BSC MSC 1X BSC Existing ANSI-41 Signaling Existing Dedicated Handoff Trunk Group(s) MGWMGCF ISUP (New) HO Appl Srvr SIP Bearer Trunks Tunneled 1X Signaling New Signaling Interface IMS

7. 7 Comparison of Approaches ANSI-41 Based approach requires:  New Handoff Function entity to perform Anchor MSC functionality.  New dedicated handoff trunk groups from the MGW to each possible handoff MSC, including additional hardware on the MSCs and MGW, and ongoing monthly circuit charges.  New signaling interface from HRPD (DO) RNC to Handoff Function. ANSI-41 Based approach Notes:  Not access-technology independent.  Proliferates ANSI-41 in the network.  Expensive solution.

8. 8 Comparison of Approaches (cont.) IMS/MMD approach requires:  New software Application Server function.  New signaling interface from HRPD RNCs to neighboring 1X BSCs to tunnel 1X signaling.  Possible expansion of existing bearer trunks between a MGW and an MSC in the serving network, though additional trunks may not be needed in all situations in an operator’s network.  Called Number routing to a local MGCF, and then SIP Invite routing to the home network, using a Public Service Identity (PSI) number. I.e., routing table updates in the MSC. IMS/MMD approach Notes:  Is access-technology independent (also works for handoff to/from WLAN and other VoIP environments).  Does not need any new ANSI-41 connections.

9. 9 Analysis and Recommendation The IMS/MMD based approach is less costly to develop and deploy. (SIP application server vs. significant ANSI-41 effort) The IMS/MMD based approach is less costly to maintain and manage. (no additional trunk groups, possible limited expansion of MGW to MSC trunks, no new ANSI-41 SS7) The IMS/MMD based approach is directly applicable to handoffs to 1X Circuit from multiple VoIP environments, including home-based WLANs. Recommendation The IMS/MMD based approach should be chosen and activities accelerated to facilitate completion of necessary standards in 3GPP2 in the needed time frame for VoIP deployments: - IOS standards begin R&F – July/August 2005 - Core network standards begin R&F – August/September 2005