IP trunking is bit too big to cover on the fly. See
www.2000stuff.com for guidance.
Once you program up the IP trunks, assign them to a trunk group. Then:
Here's the progress for LCR:
CM 200>x>a129 where x=the leading digit of extensions on the other PBX.
CM 8AA000>3>4007 (don't ask why, just do it)
CM 8A4007>xxxx>0010 (this sends calls that start xxxx to route 0010) (make additional entries to cover all scenarios)
CM 8A0010>1>050 10 (no space in programming: 05010)
(this sends calls on route 0010 to trunk group 10
with using a label called 050).
At this point, calls to your extension will go out to the IP tie trunk and send DNIS to the other side.
EXAMPLE: Call x. 3016. This extension is in the other PBX.
CM 200 sends the call to 8aa000, which refers to 8a4007. In CM 8a4007, 3016 points to route plan 0010. This sends the call to CM 8A0010, which has the first choice of trunk group 10. The DNIS 3016 goes to the other side, where the call rings on ext. 3016.
If you need to add digits or set toll restrictions, use 8A5yyy where yyy is the label that you set in the last step (in our example, it's 050, so the command is 8A5050).
WARNING: IF YOU DON'T KNOW THE IPS, It's easy to screw up important stuff this way. Beware. Take precautions. Know what you're doing. Read the database carefully.
Hope that helps.