asterisk users - Dec 2003 - Quick question on source cvs files

Hello,

I've setup some test servers, some with digium cards, FXO/FXS but none with
PRI. 
1. is it necessary to download and compile libpri source or will asterisk
function properly with just zaptel, zapata and asterisk source?
2. If I install a system just for Voip, with no digium cards, can I get away
with just compiling zaptel (ztdummy) and asterisk source?

Thanks in advance.

JR