I'm not certain, but I suspect there is a misunderstanding here.
The presence of SDP in a 1xx response permits the establishment of a
media stream from the UAC to the UAS. It doesn't matter what sort of 18x
it appears in - 180, 183, etc. It really has *nothing* to do with
rendering ringback. A
I would like share some experience on the reported issue. As you mentioned
that Volte users sending 183 SDP. So I suppose it is not related to ring back
tone for CPE user since it is only intimation of session progress for CPE or
playing tone from Volte user if there is any early media.
In O
