We're configuring Kamailio 4.2 with rtpengine to act as a midpoint between a telephone using TLS/SRTP and Asterisk. There are examples out there for TLS/SRTP with WebRTC, but we're using a plain hard phone, not WebRTC.

Would anyone be able to point us towards a Kamaiio configuration which:

a) Tests if the destination phone (stored using usrloc) uses TLS.

b) Sends RTP for calls to a TLS phone to rtpengine to be encrypted. We can assume all phones using TLS want to use SRTP.

Thanks very much in advance.