Hi Gaoqiang, MSRPRelay is not dependent on OpenSER. You can set it up separately based on the instructions available at http://msrprelay.org. You only need a client with support for the MSRP relay extension, the SIP session can be established by any version of OpenSER. I believe you refer to the MSRP chat server when you say "session switch". MSRP chat server is work in progress, no software has been released yet, we plan to release a first version this summer. Regards, Adrian Hi list, Could anyone here tell me is the openser 1.3.x version support MSRP(e.g. MSRPRelay)? Is there any document describe how to configure the openser work with MSRP(MSRPRelay) as a message session switch. Does anyone have successful experience configure openser to work with the MSRP Relay. Thanks a lot. -- Gaoqiang Qian Automation System and Technology Helsinki University Of Technology GSM: +358415058138