I have a Mitel 5000 recently switched to SIP trunks. They have a Viking analog call box configured as a house phone. The call box is supposed to call an outside number, pause, then send an extension number. The phone number configured in the house phone is 8 plus the number, followed by a pause then an extension number followed by # (8xxxxxxxxxxP183#) This worked with the POTS lines. But now when the call goes out it is sending the phone number plus extension number in the SIP INVITE and a message comes back that the number is not recognized. If I remove the extension number, the call goes through, but unfortunately the beeper requires a number or it will not beep. I've tried entering a 1 before the number, I've also inserted a # after the number followed by a pause then the extension number - call goes through but the extension number does not.

Anybody have any idea on how to get this to work?