Mitel 3300 not sending 100 Trying

[pradeepgali]

Hi,

I have connected Mitel 3300 to Microsoft Lync using SIP. Both outbound and inbound calls are working fine. When made an outbound call, Lync sends INVITE message and Mitel is sending 183 Session progress in response to INVITE. But it is expected to send 100 Trying in in response to INVITE message. Please let me know if anyone came through this issue of there is any configuration settings that i can make in Mitel to send 100 Trying. 

[sarond]

In your SIP options try setting Disable Reliable Provisional Responses to Yes.
Also try setting Ignore SDP in Unreliable Provisional Responses to Yes