[cisco-voip] SIP vs PRI PSTN

[Matt Slaga (US)]

There are actually quite a few, however most have caveats or special
functions that cause issues when directly connected to CallManager.  

 

For instance, some only provide DTMF inband, which CallManager does not
support.  You have to use an IP2IP Gateway (SBC) with DSPs to convert
in-band DTMF to RFC2833.  Some only support G711 for all calls, some
require multiple sip realms per SIP line (which Cisco currently only
supports one at this point).

 

The biggest issue is with quality concerns.  You have no control once it
leaves your network.  However, if you use TWC (or a few other sparse
ISPs) you can get SLAs for voice quality if you use their SIP offering.


 

IMHO, use SIP trunks only if your ISP can provide the service.  Or, use
someone like Broadvox who will let you "test drive" before you buy.

 

From: cisco-voip-bounces at puck.nether.net
[mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of SHAM SHARMA
Sent: Tuesday, January 22, 2008 7:58 PM
To: keli at carocomp.ro
Cc: cisco-voip at puck.nether.net
Subject: Re: [cisco-voip] SIP vs PRI PSTN

 

not many service providers support SIP yet ... SIP is future

On Jan 22, 2008 5:31 PM, <keli at carocomp.ro> wrote:

Although I must admit I probably don't understand this question (SIP
for PSTN? Isn't that a contradiction in terms? :P ) my two cents (if 
we're talking about SIP as in VoIP protocol):

You're free from quite a lot of expensive hardware (no gateway, no
E1/T1 card, no DSPs) and also, even a *lot* of bandwidth can be
cheaper that the monthly rates of an E1 PRI (well, at least this seems 
to be the case around here). Adding new PRI lines adds to costs almost
in a linear fashion (hardware has to be bought for each line just as
well), while bandwidth comes at significant discounts in large
quantities. 

Though that's just my theory, since I myself don't really see this
"trend" happening much. So far PRI is way more reliable as a
technology to be easily replaced by SIP trunks... (again, this is just 
my point of view, my circumstances etc.)

Zoltan

Quoting Lelio Fulgenzi <lelio at uoguelph.ca>:

> Is there a fundamental reason users are going from PRI to SIP for 
> the PSTN connections? Is there a cost savings realized somewhere -
> either hard or soft?
>
> I wouldn't mind hearing from the group.
>
> Lelio
>
------------------------------------------------------------------------
-------- 
> Lelio Fulgenzi, B.A.
> Senior Analyst (CCS) * University of Guelph * Guelph, Ontario N1G 2W1
> (519) 824-4120 x56354 (519) 767-1060 FAX (JNHN)
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

> "Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo."
WJR



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