[asterisk-users] Sort of OT: PBX vs CO

[Alex Balashov]

On Fri, 10 Aug 2007, Anthony Francis wrote:

> On Fri, Aug 10, 2007 at 11:37:37AM -0400, Alex Balashov wrote:
>> And as a CO switch, you *must* switch TDM; VoIP isn't really an option.
>>
>>
> Really?  http://www.pt.com/products/prod_segway_ntwksolution.html

   He said _switch_ TDM.  :-)

   There's eight million IP SS7 solutions out there.  What good does that 
do you if you are approaching this from standpoint of a CO switch?

   About the only thing you can do with Asterisk that would even remotely 
approximate a large-scale TDM switch is confer upon the sagacious 
qualities of an all-knowing call controller and enclose it in a 
shatterproof fortress of high-density media gateways like the Cisco
AS5400 & 5800, and dump TDM trunks into them.  Then you can send and
receive calls from TDM in a fairly high volume as SIP and perform some
manner of rudimentary switching.

   But it's not a true signaling / call controller.  It has no awareness
of the state of the controllers in the MGWs, nor advanced signaling
capabilities (i.e. SS7, native TDM or otherwise).  Because of this, you
cannot make your TDM interfaces scale;  you cannot tell the MGW which
trunks to use for what purpose and when, and you will have to dedicate
MGWs to certain concrete purposes ("inbound", "outbound"), which puts a
serious damper into 99% of the economies of scale for which a switch is
actually beneficial.

--
Alex Balashov
Evariste Systems
Web    : http://www.evaristesys.com/
Tel    : +1-678-954-0670
Direct : +1-678-954-0671