scope:

This Recommendation describes the framework and procedures that should be implemented by operators for establishing an interconnection between voice over long-term evolution / video over long-term evolution (VoLTE/ViLTE)-based networks to achieve worldwide interoperability.

This Recommendation identifies additional scenarios and requirements for VoLTE/ViLTE interconnection which have not been defined in existing 3GPP standards and GSMA guidelines, as follows:

- possible E2E scenarios in terms of interconnection and roaming;

- description of the EPC functions which should be supported;

- EPC configuration requirements;

- device and U/ISIM requirements;

- comparison of VoLTE roaming architecture;

- list of mandatory and optional services which should be supported by operators for interconnection and roaming scenarios;

- protocol implementation statement (PICS) needed for the service level agreement (SLA).