I'm trying to get SRTP working on our 504s and 525s. I've uploaded a mini-certificate (and private key), set 'Secure Call Serv' to 'Yes', and set 'SRTP method' to 's-descriptor'.
When the phone receives a valid RFC-4568 offer, it happily encrypts the session (and plays the tones, displays the '%' sign on the screen, etc.)
But the phone *never* offers SRTP on outbound INVITEs.
What am I missing?
Should I be doing something else?