There is an AVP 1493 (Homogeneous Support of IMS Voice Over PS Sessions) that might be sent or not within ULR message. According to 29.272, this AVP is presented in ULR if either all TA/RA of the MME homogeneously support VoLTE (AVP 1493=Supported) or non of RA/TA of the MME supports VoLTE (AVP 1493=Not_Supported). According to 29.272, the AVP 1493 value =“NOT SUPPORTED” may also indicate the lack of VoLTE roaming agreement between HPMN and VPMN. AVP 1493 is not presented in ULR if some of RA/TA support VoLTE and some not or MME has no info about VoLTE support.
I have several questions:
1. I assume MME will not include the AVP 1493 in ULR if UE has not requested voice over PS. Is this correct?
2. Whether MME inserts the AVP 1493=Not_Supported in ULR towards HPMN when there is no VoLTE roaming agreement irrespectively to UE request for voice over PS or only when UE has requested for voice over PS?
3. How MME decides about VoLTE support on TA/RA level(configuration, dynamic conditions etc.)?
4. What could be scenario when MME has no info about VoLTE support?
5. Whether the case when AVP 1493 is not presented in ULR due to reasons defined in 29.272 is common or it is just intermediate state while VoLTE deployment?
