Installation and Configuration Manual
4. Configuring the Enhanced Media Gateway
SBA for Microsoft Lync
87
December 2010
4.9
Defining Early Media
Early media refers to audio and video that is exchanged before a call is accepted by the recipient.
Early media generated by the caller includes voice commands or dual-tone multi frequency
(DTMF) tones to activate interactive voice response (IVR) systems. Early media generated by the
call recipient include ringback tones, announcements, and requests for input.
Enhanced early media support in Lync 2010 enables a caller to hear a ringback tone generated
by the call recipient’s mobile phone. This is also the case in team call scenarios, where a call is
routed to two team members, one of whom has configured simultaneous ringing for his or her
mobile phone.
According to Lync 2010 requirements, the AudioCodes Media Gateway should send 183 with
SDP, immediately after it receives an INVITE. The RTP packets however, will not be sent until the
Media Gateway receives Progress, Al Progress Indicator or Connect from ISDN. For
example, if the Media Gateway receives ISDN Progress, it starts sending RTP packets according
to initial negotiation, but there is no need to send again the 183 response.
You may need to change the Media Gateway's early media parameter to support Lync 2010
enhanced early media feature.