Quadro ISDN Gateway SIP Proxy / Client - Connect to SoftPBX.

[armonis]

Greetings to the community.

After a long search and trials, I am still in problem finding a way of realizing the following scenario:

Items on hand:
1. Axon SoftPBX (192.168.0.133)
2. Q. ISDN Gway WAN: 192.168.0.125, LAN: 172.28.0.1
3. LinkSys SPA941 SIP Phone (192.168.0.118)
4. ISDN NT Adapter with 2 ISDN BRA from Local Telephony Provider

Goal:
Using the Axon SoftPBX, place calls and receive calls at the SPA941. All the automatic attendant features and other stuff will be handled by Axon.

Done so far:
1. Achieved to place calls from SPA941 to ISDN by using Asterisk and applied the following configurations:
Astersik / extensions.conf
exten => _8XXXXXXXXXX,1,Dial(SIP/${EXTEN}@192.168.0.125)
exten => _8XXXXXXXXXX,3,Congestion

Quadro / Call Routing Table
Patterns: * Pattern Modification: NDS:1 Call Settings: ISDN trunk: Any Port(User)

The reason I used Asterisk is because it allows calls to be placed using any provider WITHOUT using a specific account. By selecting the Quadro as "provider", it just sends the call to it and the Quadro gets the ISDN line of hook.
The Axon need a valid Username, Password, Proxy and Port. These are basic needs of any SIP client.

How can we setup SIP user registration parameters for each ISDN channel?
How can we route any incoming call from the ISDN to these accounts?

In this way, Axon will just add an external line that will be registered to the Quadro and that's ...all!

I have seen that the option PSTN lines sharing could help but it only works with the existance of a Quadro IP PBX.

Any help is needed.
Thank you.