[ale] [OT] Re: Sip maturity

[Michael B. Trausch]

On Sun, 2008-04-20 at 22:07 -0400, Ashley Wilson wrote:
> What is the general consensus on the maturity of SIP (from a
> reliability standpoint) for small call centers?  I really like the
> idea of being able to fail-over to a second SIP enabled IP telephony
> system in a DR facility in the event of disaster.  But I have gotten
> warnings from people who may have a monetary interest in using a PRI
> based system. 

SIP---as a protocol---is quite fine indeed for handling phone calls.
However, it (or any VoIP protocol such as IAX2) pretty much requires
that you have some network that you control for it to be useful.

If you have Call Center A, and Call Center B, and Call Center B is a DR
call center that is presumably many, many miles away, your best best for
reliability is probably to have a heartbeat link between them, lots of
lines from the telco, and have those all going into a server that is
your internal PBX system at both locations.  The only thing that you'd
really have to figure out is how to re-direct the incoming calls to the
second location when necessary.  Presumably the phone company can help
with that if you've got any volume of lines, but someone with a bit more
experience in setting up large phone systems can tell you for sure.

However, I wouldn't route VoIP over the Internet for a large system
unless you have LOTS of bandwidth and the ability to guarantee the
reliability between the two points on the Internet.  SIP most often goes
over UDP, which means that packets can be (and often are) lost over the
Internet, and TCP/IP based protocols (such as IAX2) don't have that
issue so much, but there can be increase latency, because TCP/IP has
certain guarantees associated with it (when the network connection is
up, anyway).

Short story:  I'd use, if at all possible, large pipes with the
telephone company if I needed something that was absolutely reliable,
and then have the internal PBX be VoIP-based.  Setting up your own VoIP
PBX is actually far easier (and can be far cheaper) than using a
"standard" PBX solution from one of the many companies out there, and if
you have the network under your control, you can ensure that the
bandwidth is available for the call load that the network will be
handling.

	--- Mike

-- 
Michael B. Trausch                                   mike at trausch.us
home: 404-592-5746, 1                                 www.trausch.us
cell: 678-522-7934                       im: mike at trausch.us, jabber
Ubuntu Unofficial Backports Project:    http://backports.trausch.us/

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