SIP Trunk to 8x8 / RingCentral

[holycow90]

I'm going for a long shot here and hoping someone can point me in the right direction in setting up a SIP trunk to our 8x8 provider that we are using in a small office.  We have already purchased a SIP trunk that they gave us with an IP and port to use.  We have a dedicated / routable internet IP to our PBX with the specified SIP ports.  I believe we have what we need to get this working but I am completely oblivious on what to do from here.  I've created a new network element to 8x8, created a SIP Profile to use that element, and created a ARS Digits dial section to specify a range of extensions that we have in 8x8. When I attempt to call an extension in that range I just get nothing on the phone.  I have 8x8's SIP interface specifications PDF but it is over my head unfortunately.  I've created a ticket with Mitel but in my experience they aren't very helpful with these kinds of things.  We are running MiVoice 8.0 SP3 PR2

[acejavelin]

The Mitel 3300 requires a SBC of some kind for SIP trunking in most cases... Either a Mitel Border Gateway or other SBC like Adtran or AudoCodes, since the Mitel does not support NAT in any way.

Programming is a little more complex and has some gotchas in the Mitel, even in the basic trunking, like your Trunk Attributes must have a Dial In Trunks Incoming Digit Modification - Absorb defined, even if that is 0. There are plenty of "general" SIP trunking guides in the Mitel knowledge base, have you gone through any of those?