Monday, January 10, 2011

Lync and ‘telephone-event’ in the sdp

An interesting little nugget in the nice new Lync client now it has the (love it or hate it) dial pad.

When an incoming SIP Invite sdp offer includes the ‘telephone-event/8000’ payload (also known as RFC 2833 out of band DTMF) the UI looks like this:


When it doesn’t, it looks like this:


Notice that the dial pad button has now disappeared.