[Asterisk-Dev] signal gateway access

[Mike M]

On Mon, Oct 25, 2004 at 07:40:08PM -0700, Kevin P. Fleming wrote:
> Mike M wrote:
> 
> >What do you think about an external signal gateway
> >that delivers signal packets to Asterisk over IP?
> 
> Isn't this what SIGTRAN is for?

Absolutely.
> 
> >UDP would work on a back-to-back connection.  TCP/TALI
> >might work but it's esoteric.  SCTP/M3UA would be 
> >a good general solution.  I've been following the LKSCTP 
> >project for a while now and sense that it might be ready to use.
> 
> There is also AudioCodes' proprietary (?) implementation of SS7-over-IP.

UDP works better than you might think, but only as a fast start.  Using 
SCTP/M3UA depends on how well Asterisk and LKSCTP play together.

AudioCodes offers "M2TN" which is a branded version of SCTP/M2UA.
They do interworking so they are good guys.

Going with SIGTRAN protocols makes sense so that many products will
work with Asterisk.
> 
> >What do you think about the signal gateway converting between ISUP
> >and Q.SIG/Q.931?  The idea comes from knowing that Asterisk
> >has a PRI interface that could become the base for an IMT
> >control interface.  With conversion, the Asterisk changes
> >would be minimized.  
> 
> True, but you would lose access to any features beyond what Q.931 allows 
> (which you already alluded to... CNAM, LNP, etc).

Good point.  As a starting point though, converting to Q.931 would work for
basic calls.  If there is sufficient interest, then perhaps an ISUP based
IMT call engine could evolve.  Or would it make sense to start with the
ISUP handler in Asterisk?
> 
> >Separating the SS7 functions from the Asterisk platform offers
> >some advantages.  SS7 network providers are intolerant of links
> >going in and out of service so having a dedicated and redundant
> >platforms ensures stable operation of SS7 links.  An external 
> >signal gateway is also capable of serving several (maybe even 
> >many) Asterisk boxes.
> 
> I also have thought that keeping the "raw" SS7 away from Asterisk would 
> make a lot of sense, and would make adoption (at least the US) an easier 
> process.

Outside North America too.  

-- 
Michael Mueller