Single Radio Voice Call Continuity (SR‐VCC)

From a 3GPP presentation by Hannu Hietalahti

1. SR-VCC use case

1a. IMS call initiated in LTE can continue in CS domain after moving outside of LTE coverage area

1b. SR-VCC is invoked if no other VoIP capable PS system (e.g., HSPA/eHRPD) is available for VoIP PS-PS HO (Handovers)

1c. Only HO of a single voice bearer from PS to CS is specified

1d. Requires overlapping with 1xRTT/GSM/WCDMA coverage

2. SR-VCC allows a voice calls are anchored in IMS

2a. One-way HO from PS to CS systems (LTE to GSM/UMTS or LTE to 1xRTT)

2b. No simultaneous operation of different radio transceivers needed

3. Rel-9 SR-VCC improvements

3a. IMS support of mid call services (e.g., HOLD, MPTY)

3b. SR-VCC support for emergency calls

4. Video calls, reverse direction from CS call to IMS and optimisations are being studied in Rel-10