pbx system for leopard

[Mike's Western Account]

hi all;
so i tryed asterisk, and kept getting an error that
/library/asterisk/run/asterisk.pid
couldn't be ran and btw there wasn't any file in /library/asterisk/run/ 
asterisk.pid
anyways is there a good pbx system i can run on my macbook using sip  
and what not? I just want something to mess with, or am i doing this  
wrong to get asterisk set up? Going into terminal and typing simply  
"asterisk" after running the package installer i downloaded. Any help  
would be wonderful
thanks
Mike