[asterisk-ss7] ANNOUNCE: libss7

[Matthew Fredrickson]

Hey all!  For the past year I have been working on and off on an SS7 
implementation here at Digium called libss7.  I have it to the point 
where it can pass phone calls, so I figured it would be a good time to 
release it and let people begin testing it.  It's still somewhat "bare 
bones" in functionality, but I've been doing a lot of fleshing out of 
the implementation.

Currently, it has been used (making and receiving phone calls) and 
developed in an ITU SS7 environment, but I have a good chunk of the 
code included which is required for ANSI support as well.  I think I'm 
going to get an ANSI link in a few weeks, so hopefully I'll have that 
tested and working relatively soon.

It supports MTP2, MTP3, and ISUP.  After I get these layers fleshed 
out, I'm planning on starting on SCCP and the layers above that with 
the eventual goal of database-lookup and SMS support.

To test, you must have a T1/E1 card as well as an SS7 link.  You also 
need to have zaptel installed on your system.

Here are the instructions for checking it out of subversion and getting 
it working:

`svn co http://svn.digium.com/svn/libss7/trunk libss7`
`cd libss7`
`make install`

Right now, the changes to chan_zap are implemented in a special 
developer branch of asterisk. These are the instructions to check it 
out
`svn co http://svn.digium.com/svn/asterisk/team/mattf/asterisk-ss7 
asterisk-ss7`
`cd asterisk-ss7`

If you haven't compiled trunk yet, you may have to run `make` a few 
times so that the configure script runs and sets things up properly.  
It should find libss7, and compile chan_zap with support for it.  The 
link is brought up automatically when Asterisk starts.

Configuration in zaptel.conf is similar to that of a PRI.  Your 
signalling channel will be set as a "dchan" and the bearer channels are 
set as "bchan".  For information about setting up zapata.conf, see the 
sample zapata.conf in the configs/zapata.conf.sample in the 
asterisk-ss7 branch.  There also is a libss7 project section on Mantis 
now for any bugs that you might encounter.

Matthew Fredrickson