Digium configuration for PRI PBX usage, and PRI client usage


I want to create an asterisk PRI PBX with ISDN only capability, as leasing a PRI line from telco would be more expensive.

Is it possible to test the asterisk PBX functionality without a client PRI card? (ie. by typing 'dial ’ and see what happens).

Next I want to write my own PRI application for the client card for making and receiving calls and send/receive audio on them. The only source I think I can use is the ‘channel_zap.c’ which is not well commented.
Is there any other sample codes or well documented API for programming the PRI TE110P card (handline events, what are the distinct events for, …)?

Thanks in advanced
Tamas Patai