[cisco-voip] Setting up 2610 as a SIP gateway to PBX

[x25 at pobox.com]

I've been given a task which I am not familiar with, so I need some help.

Basically, the idea is to connect 2610 router with a PBX, over T1 PRI, and then allow other devices 
(Asterisk, for example - or even an ordinary SIP softphone) to make calls through PBX via Cisco gateway.

Something like this:


Asterisk ----- SIP -----> 2610 -----> T1 PRI -----> Mitel 3300 PBX


I have configured 2610 and brought T1 link up. Hoever, I am bit lost as to how I need to configure router in 
order to allow SIP clients talk to PBX. SIP is IP based protocol, so I presume 2610 will do some voodoo 
conversion before sending it to PBX. I do have username/password for PBX, just need to find a way to register 
a SIP client over this link (can't talk SIP directly to 3300).

So, I have controller and serial interface setup:

isdn switch-type primary-dms100

controller T1 1/0
 framing esf
 clock source line primary
 linecode b8zs
 cablelength short 133
 pri-group timeslots 1-24
 description Link to Mitel 3300

interface Serial1/0:23
 no ip address
 encapsulation hdlc
 isdn switch-type primary-dms100
 isdn incoming-voice voice
 no cdp enable

And at this point, I am bit lost. After trying to read lots of documentation, I've reached the "information 
overload" phase, where I am more confused than before, so I need help :)

I assume that I also need dial-peer defined, like this (this was just for testing)

dial-peer voice 1023 pots
 destination-pattern .T
 port 1/0:23
 forward-digits all

Could anyone just explain basic steps (and which features are needed) in order to make this work?

I tried adding random things to configuration (sip-ua enabled, then enabling voice service voip, etc), but 
the main problem is that I don't understand what I need exactly, so any help is welcome :)

Thanks.