3GPP VCC Call Control Procedures

1. Call origination from the IM CN subsystem



2. Call origination from CS domain



3. Terminating call directed to IM CN subsystem



4. Terminating call directed to CS



5. Terminating call coming from CS domain (using CAMEL)



6. Terminating call coming in through CS domain and delivered through the CS domain (1)



7. Terminating call coming in through CS domain and delivered through the CS domain (2)



8. CS domain to IM CN subsystem call transfer



9. IM CN subsystem to CS domain call transfer

UMTS to GSM Handover procedures

1. Basic handover procedure requiring a circuit connection between 3G MSC-A and MSC-B (UMTS to GSM)


2. Basic handover procedure not requiring the establishment of a circuit connection between 3G MSC-A and MSC-B (UMTS to GSM)


3. Subsequent Handover from 3G MSC-B back to MSC-A (UMTS to GSM)


4. Subsequent Handover from 3G MSC-B to MSC-B’ (UMTS to GSM)


5. Subsequent Handover from 3G MSC-B back to MSC-A without circuit connections (UMTS to GSM)


6. Subsequent Handover from 3G MSC-B to MSC-B’ without circuit connections (UMTS to GSM)


7. Circuit-switched call establishment after a Basic UMTS to GSM Handover without circuit connection (UMTS to GSM)

GSM to UMTS Handover Procedures

1. Basic handover procedure requiring a circuit connection between MSC-A and 3G MSC-B (GSM to UMTS)



2. Basic handover procedure not requiring the establishment of a circuit connection between MSC-A and 3G MSC-B (GSM to UMTS)


3. Subsequent Handover from MSC-B back to 3G MSC-A (GSM to UMTS)


4. Subsequent Handover from MSC-B to 3G MSC-B’ (GSM to UMTS)


5. Subsequent Handover from MSC-B back to 3G MSC-A without circuit connections (GSM to UMTS)


6. Subsequent Handover from MSC-B to 3G MSC-B’ without circuit connections (GSM to UMTS)


7. Circuit-switched call establishment after a Basic GSM to UMTS Handover without circuit connection (GSM to UMTS)

UMTS Handover Procedures

1. Basic handover procedure requiring a circuit connection between 3G MSC-A and 3G MSC-B


2. Basic handover procedure not requiring the establishment of a circuit connection between 3G MSC-A and 3G MSC-B


3. Subsequent Handover from 3G MSC-B back to 3G MSC-A


4. Subsequent Handover from 3G MSC-B to 3G MSC-B’


5. Subsequent Handover from 3G MSC-B back to 3G MSC-A without circuit connections


6. Subsequent Handover from 3G MSC-B to 3G MSC-B’ without circuit connections


7. Circuit-switched call establishment after a Basic UMTS to UMTS Handover without circuit connection

GSM Handover Procedures

1. Basic handover procedure requiring a circuit connection between MSC-A and MSC-B


2. Basic handover procedure not requiring the establishment of a circuit connection between MSC-A and MSC-B


3. Subsequent Handover from MSC-B back to MSC-A


4. Subsequent Handover from MSC-B to MSC-B’


5. Subsequent Handover from MSC-B back to MSC-A without circuit connections


6. Subsequent Handover from MSC-B to MSC-B’ without circuit connections


7. Circuit-switched call establishment after a Basic GSM to GSM Handover without circuit connection

Voice Call Continuity: 3GPP v.s. 3GPP2 -- Registration

1. Background

For supporting VCC acrossing the traditional circult domain and new IP packet domain, a VCC UE needs to perform its traditional circuit domain registration as usural and an additional IP packet domain IMS registration.

2. 3GPP VCC Registration




3. 3GPP2 VCC Registration

Voice Call Continuity: 3GPP v.s. 3GPP2 -- Architecture

1. Some background information

VCC is a 3GPP and 3GPP2 concept referring to the voice call continuity function in the new IP based IMS mobile core and the traditional circuit based mobile core convergence environment. VCC function will not only provide mobile operators the capability of non service interrupting seamless network evolution, but also enable them with new service accessing methods (such as WiFi, wireline, WiMax etc.) and new service capabilities (such as domain transfer etc.).

In both 3GPP and 3GPP2 worlds, there are two major VCC functions, respective the single radio VCC (SRVCC) which addresses the VCC function over the same radio but different air access methods: circuit and packet accesses respectively, and multiple/dual radio VCC which addresses the VCC function over different radio frequencies and access methods such as ordinary mobile access and WiFi/WiMax access etc.

Here we will focus on the comparison between the 3GPP and 3GPP2 multiple/dual radio VCC functions.

2. 3GPP VCC Architecture Reference Model




3. 3GPP2 VCC Architecture Reference Model