Originally Posted by doghart
UPDATE:
Upgraded the Shoretel from 12.3 to 14.2 and SIP connection between the the Shoretel & Cisco is now working flawlessly using the settings listed above.

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Thanks for sharing. I had a feeling that 14.2 would work better then 12.X with SIP trunks.

I just tied our Shoretel to Toshiba in a lab using SIP trunks and got it working pretty easily. A few years ago I tried to do the same thing and failed. Either I did not know as much back then about SIP trunks or the Shoretel and Toshiba software improved with SIP trunking. I think it may be a combination of both.