Hello Regarding on Implementation the Music On Hold with Opener as SIP Proxy. As I know OpenSER is not Media Proxy Server. But I want to implement below call flow, that Bob has to Send the REFER method To Media Server ( Asterisk ). But I Don't want this ( Alice --invite_bob---> OpenSER ---- invite_bob-->Asterisk-----invite_bob---> openser---> Bob ) this scenario will work .. That User Agent has to send the REFER method to OpenSER Proxy through --> Asterisk. Alice Bob Media Proxy.. *Plz let me know, If anything is missed or something is else...* *Thanks & Regards* *Ravi Prakash Sunkara* VoIP Development Tech Lead