[Asterisk-Users] Asterisk <--> PABX

[rudolfl at optusnet.com.au]

Hi, all

I have been asked if it will be possible to conenct Asterisk to a commercial PABX.

Company has an established call center, but want to use Asterisk for long distance
inter-office calls and they want to use existing phone system.
At the moment all I know is that they have Siemens PBX system. They will give me
more details soon.
Since I never tried that before, I want to get some information before I even talk
to them.
Did anyone try to connect to an office PBX? What interfaces PBX typically expose?
What to look out for? 
Any links will be greatly appreciated.

Thanks,
Rudolf