Can someone give me the call flow of Handover from 3GPP access to Trusted Non-3GPP IP Access with MIPv4 FACoA on S2a ?

Question

As per my knowledge, WiFI calling is supported over untrusted(using ePDG/S2b) networks from Rel 10 onwards.
But I am not sure about WiFi over trusted(TWAG/S2a) networks and having few doubts.

1. Is VoWiFI is supported over trusted(using TWAG or S2a) networks, if not then what are the limitation?
2. Is LTE to WiFI handover supported over S2a interface(TWAG) ?

Any help, pointers will be appreciated.

Answer 1

Actual call flow i don't know but with help of specification i can tell you some information that i have found.

The steps involved in the handover from 3GPP Access connected to the EPC to trusted non-3GPP IP access are depicted below for the case of non-roaming, roaming with home routed traffic, roaming with local breakout and roaming with anchoring in the Serving Gateway in the VPLMN. It is assumed that while the UE is served by the 3GPP access, a PMIPv6 or GTP tunnel is established between the S-GW and the PDN GW in the evolved packet core.

TS 23.402 Section 8.2.2