[SR-Users] Regarding RTP in IMS Networks.

Hi all, I have a doubt w.r.t media traffic in IMS Networks. If I have a setting as follows - User 1 Making the call + plays RTP Traffic User 2 Answering the call + records the RTP Traffic coming from User 1 and does a PESQ voice quality analysis I see that User 2 has to play RTP Traffic before it can start recording the RTP coming from user 1. i.e., User 2 Answering the call + (Play RTP Traffic ) + records the RTP Traffic coming from User 1 and does a PESQ voice quality analysis. Why am I seeing this behaviour. Is it just a setting in the IMS network that can be changed or is it a standard behaviour in IMS Networks ? If yes, then could anyone please let me know the logic behind such a decision? Please do let me know if you have any ideas. Any responses really appreciated ! Thanks, Badri.