iPhone Asterisk project is a port of the Asterisk PBX to the Apple iPhone. It is still in early testing, but it complies, runs, and handles calls without issue. I am working on submitting my asterisk changes to Digium, but until then I've put a binary and source release below. To get the source release to complile, you need a working iphone and have the iphone cross complier working.
The first port of Asterisk 1.4.13 is done and working. All the code is released under the GPL v2.
Tested with iPhone firmware 1.0.2, not tested with 1.1.1.
How do I install Asterisk on my iPhone?
1) Make a new dir on your iphone (/usr/local/asterisk)
2) Copy all the files from the tarball into that directory
3) Execute /usr/local/asterisk/sbin/asterisk
4) Connect to the cli: /usr/local/asterisk/sbin/asterisk -r