Since I tried chan_mobile eons ago (Configuring, using and debugging chan_mobile on Asterisk) and then revisited it (chan-mobile on Asterisk 1.4) just to inform people who were looking for information, I have seen people visiting snapvoip to find more information.
Since I have dumped my Asterisk 1.4 and moved on to Asterisk 1.6, I did not pay much attention to it because it is working for me.
For those who are interested, chan_mobile.c is in the trunk of asterisk-addons (http://svn.digium.com/view/asterisk-addons/trunk/channels/). But it seems a lot of people are having trouble running it on Asterisk 1.4 again. So murf from Asterisk Development has taken the task upon himself to come to the aid of those souls who were beating their heads against walls computers and desks.
Murf has written a very comprehensive write up step by step (23 steps all in all). I think anyone will find the procedure easy to follow to get the chan_mobile working on their Asterisk 1.4.
Here are the first three steps (out of 23) from Murfs blog;
1. wget ftp://www.parsetree.com/chan_mobile-backport-1.4
2. download the bluez-4.24.tar.gz file from bluez.org; unpack
it and have it ready; you don't need to compile it, but
you will need the test/simple-agent script. You'll only
need this, most likely, if your Linux kernel is late-model,
and using the latest version of the bluez stuff.
3. if you are interested in what changes I made to the trunk
version of chan_mobile.c, then:
(you don't need this, but you might be interested
in what I did).
Here is the post; Backport chan_mobile to 1.4