[Asterisk-Users] How does Asterisk use CPU?

[Matthew Asham]

Hello,

I'm trying to figure out what portions of Asterisk need a lot of CPU
time.

I thought I read somewhere that a Dual P4 2.something will support
approximately 80 calls.  Is this based on calls that Asterisk is
actively doing voice processing for (say, Zap channels and voicemail)?

Would a SIP client going through Asterisk and out an IAX channel be
CPU intensive if I kept the codec the same throughout the path?

I'm probably not asking very clearly, it's awefully late (err,
early) but any pointers would be greatly appreciated.

Thanks

Matthew