Hello Andy, SER MediaProxy has fail-over mechanism and achieve what you want. Using DNS SRV records you may distribute the load among any number of boxes you have. http://www.ag-projects.com/SER_Media_Proxy.html -- Adrian Hi Jan, thanks for your answer. however, How does this solution scale? I may have a large number of users behind NAT. Is it possible to have a failover.. i.e. send to to rtpproxy1, if it is down/busy send to rtpproxy2, rtpproxy3, etc? From what I can see in the source code there can only be one rtpproxy at a time. Is this correct? Or am I missing something. Is anyone deploying a large number of users using rtpproxy? What have you found? regards, Andy