Here's an update:
I have been talking to Genband and they have what they refer to as SIP-PBX Trunks geared to work with IAD's and SIP Trunk Capable PBX's. I will need to buy these licenses so that I can test with an Adtran TA 908e. I would really appreciate any input on how to configure the TA 908e so it syncs with my C15 Softswitch. I will place an order for one TA 908e first thing tomorrow morning.
You can contact me if you want some advice. I have a C15 and i use the TA both to sip trunk to and sip fxs, pri, etc. I could help you out.
Hood Canal Communications
360 898 2481 x205
I see that John has offered to assist on this post. If/when the issue is resolved please come back to this thread and provide an update so others can benefit from the solution.