Learn how to provide enhanced media capabilities (such as music on hold playbacks, PIN prompts, barge-in services, etc) to calls that are passing through OpenSIPS SIP Proxy. SIP proxies, by definition, lack the ability to do any media handling, due to the fact that they only stand in the path of call signalling, but not call media (as opposed to a B2B media server, which behaves as an endpoint for both media and signalling). So, how do you keep your OpenSPIS as a performant SIP proxy, but also enhance your SIP service with extra media capabilities? Starting version 3.1, OpenSIPS provides the means of controlling and changing the RTP streams of the ongoing calls without altering the signalling path of the call (i.e. without transferring the call to a B2B media server), as the calls should be easily resumed to its initial state.