[cisco-voip] Verizon SIP vs. PRI?

Buchanan, James jbuchanan at presidio.com
Mon Feb 14 09:24:30 EST 2011

One note on the T38.

I've hit this with multiple SIP providers where T38 relay is simply not supported. The workaround is to basically send fax calls through a back-to-back T1 card. Take the inbound VoIP call, send it outbound to one side of a T1, it'll come out the other side, and voila! If you know ahead of time, and have an idea of where the fax server is, this is a pretty easy workaround.


James Buchanan | Technology Manager, UC | South Region | Presidio Networked Solutions
12 Cadillac Dr, Suite 130, Brentwood, TN 37027 | jbuchanan at presidio.com<mailto:jbuchanan at ctiusa.com>
D: 615-866-5729 | F: 615-866-5781 | www.presidio.com<http://www.presidio.com/>
CCIE #25863, Voice

From: cisco-voip-bounces at puck.nether.net [mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Tony Edwards
Sent: Monday, February 14, 2011 3:02 AM
To: Lisa Notarianni
Cc: cisco-voip at puck.nether.net
Subject: Re: [cisco-voip] Verizon SIP vs. PRI?

here is my limited understanding..

1) sip / cube trunk is certainly looks promising , however , when you build a business case , make sure you add up any wan bw upgrade costs to accommodate x number of concurrent g711 calls for example. with all overhead , some telcos recommend 100k for a g711 call , so you got to budget 500k for rtp streams straight away on the same wan pipe , where your data apps will flow. so , the costs savings of not buying e1 or t1 trunk & not buying e1 or t1 controller cards on the voice gw can easily disappear , if you do maths for sip trunk wan bw upgrade.

2) secondly , I gather they still have some having issues , even though theoretically , t.38 should work well on this trunk. so you got to talk with telco closely with their own offerings. in a worst case scenario , you can still run some vg based faxing or even direct pstn if you few fax machines on a given site.

3) watch out issues with sip profiles , which are essentially like voice translation rules on h323 gw, where you match & replace digits. depending upon telco , you got to send your ani with the realm name , rather than cube's ip address.

4) depending upon flow around or  flow through deployment , you need to configure mtp at ccm.

5) also , some times i have seen issues where sip trunk in ccm pointing to the loop int of cube. it got fixed when i changed to its wan interface at one of my cube cut overs.

finally , my biggest concern is the number portability of pstn & isdn in to sip platform , which i gather is still an issue with some of the telcos around the world.

also do not forget to configure the wan qos on 5060 port for sip traffic when you role out a cube on production network.

other than that , i reckon sip cube trunks are very valid alternative to $$ expensive pri trunks.


On Wed, Feb 9, 2011 at 6:13 AM, Lisa Notarianni <notariannil1 at scranton.edu<mailto:notariannil1 at scranton.edu>> wrote:
We currently utilize PRI trunks as fail over and backup.  They connect to our 6509's.

Can anyone share their thoughts on SIP vs. PRI services.


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