SIP vs. PRI/POTS

routerdork · February 13, 2015, 08:59:29 AM

I'm curious if anyone is using SIP in place of a PRI or POTS? Why or why not would be awesome?

wintermute000 · February 15, 2015, 08:08:12 PM

Pretty much all new installs (in the first world anyway...) are SIP. Well, in Oz anyway.
PRI is last century.....

deanwebb · February 16, 2015, 08:58:27 AM

And POTS is last *two* centuries...

javentre · February 16, 2015, 09:12:38 AM

We're still on DS3s, and we have a lot of them. Our voice folks are really old school voice people and are fairly clueless about IP.

I doubt we'll switch until forced to because our preferred vendor no longer offers support.

routerdork · February 19, 2015, 11:47:45 AM

I have a lot of sites using phone systems that were installed in the late 70's and early 80's. I'm going through each site and determining what it will cost to upgrade to VoIP. As I do this I'm re-evaluating PSTN access. Every one of our sites has a local internet connection but I'm not sold on the reliability of voice over the interwebs.

LynK · February 24, 2015, 11:32:51 AM

Almost everyone uses SIP now.

The only time we do not use sip, is if it is not available in a certain area, then we use POTS lines. We do have a few sites which are limited to POTS only.

At HQ we are using PRIs, but that is because we have an old-as-dirt mitel system... soon to be upgraded to cisco VoIP... hallelujah!

JitterJabber · May 15, 2015, 05:05:49 AM

I work on a lot of sites where PRI's are the norm, but any new deployments are fully SIP and many PRI customers are migrating to SIP.

SIP is awesome because:

Migration of local numbers to any geographic location allowing for the removal of local PRI circuits
Load balancing over multiple SIP circuits to provide redundancy
Easier to troubleshoot
Bandwidth can be easily flexed depending on demand and business requirements. This is great for people in the outsource space where there are peaks and troughs in call volumes
Multinational businesses find it easier to work with the same service provider across different global site locations

dlots · May 15, 2015, 08:59:20 AM

My old job had some pretty big call centers at it, I think we saved a few hundred thousand dollars by switching to SIP (Cisco call manager). I honestly can't think of any reason to go with POTS now days unless you just don't have the staff to support SIP and your to small to get said staff.

If you want to save money imagine replacing your PBX with an open source Asterisk box, all your T1s that use to carry 24 calls now carry 65 calls (assuming you use something like a G.729 codec, if your using G.711 you actually can carry fewer calls). SIP is pretty standard now days so you aren't locked in to that 1 vendor who makes your PBX.

Standardized interface of Ethernet, no more 6 types of E&M connectors, or million different types of T1 signaling, ground-start, loop-start-E&M wink-start (there are a million of these, are your time slots lined up, what's your ISDN switch-type? I have never seen an analog T1 link work from the ISP on the 1st install)

Also your network already spans your campus, why maintain 2 sets of infrastructure (1 phone, 1 network) that goes to literately every person's desk when you can just run 1 cable, to a switch and rip out all those 110 blocks that are everywhere and horrible to work on.

If you don't mind soft phones you can also eliminate the expense of phones, also that means your phone follows the person around, that means if you want you can totally eliminate your physical call centers by having everyone work from home, that means no space for the people, no power for them, no cubicals, no heating/AC, no maintenance people vacuuming that space, picking up that trash, etc. (you can still have people work from home with a physical IP phone if you want). This doesn't just apply to call centers, but anyone who's work doesn't require a physical presence. SIP also isn't just voice, it also does video conferencing and such. I have never seen a POTS system that will e-mail your voice-mail to you either.

There is basically free long distance, but that really isn't much of a selling point

What can your god... err sorry. What can your POTS do to compare with this?

LynK · May 18, 2015, 12:34:20 PM

Quote from: dlots on May 15, 2015, 08:59:20 AM
What can your god... err sorry. What can your POTS do to compare with this?

What we are going to be doing for our new phone system is this:

-2 routers (3925's)
-Both will be running un-registered SIP to the provider (for fail over)
-We will have 1 backup PRI in each router (in case of SIP failure)
-We will also have 8 total backup POTS (backup of a backup, in case of unfortunate SIP/PRI failure)

routerdork · May 19, 2015, 09:29:11 AM

We have locations on 6 continents so it makes things rather tough when you aren't dedicated all the time to voice. My biggest issue is that I'm an R&S guy with some VoIP knowledge. I can do the basic day to day things but this isn't my career path. I'd rather do security over voice. Some of these places it's very hard to find SIP. I've got a good general design for things but with so many different rules and regulations I'm sure I'll screw something up. I told the boss I'm not here to do voice, he disagreed. That was an RGE for me!

dlots · May 19, 2015, 11:13:45 AM

Personally I think I would try and get SIP at 1 point and have great QoS to move the voice traffic to that one point.
Someone please holler if you disagree

routerdork · May 19, 2015, 12:13:47 PM

Quote from: dlots on May 19, 2015, 11:13:45 AM
Personally I think I would try and get SIP at 1 point and have great QoS to move the voice traffic to that one point.
Someone please holler if you disagree

This is very much like what we are planning for. We are looking at doing a Call Manager/Unity Connection cluster per continent. Each cluster would have it's own voice router for centralizing connections to the PSTN. And SIP connectivity between continental clusters. Right now all the data networks follow this architecture. Just tough to bring it all together.

Otanx · May 19, 2015, 01:20:17 PM

How do you handle 911 (or other country equivalent) in that design?

-Otanx

routerdork · May 19, 2015, 01:53:15 PM

So far the idea has been to leave 1-2 POTS lines at each site for SRST mode and 911. That is in the states at least. I'm still learning all the international stuff.

LynK · May 21, 2015, 09:23:51 AM

Quote from: routerdork on May 19, 2015, 09:29:11 AM
I told the boss I'm not here to do voice, he disagreed. That was an RGE for me!

There is a way in how to go about saying this, and you unfortunately went down the wrong path. The correct answer would to be honest in your limitations in the voice area, tell them you are open for training, or that you would suggest to hire a consultant to design the environment, while you 'over-the-shouldered' the project.

They will create the template for you to use for your company, you gain the knowledge in doing so, and make sure you ask for DETAILED DOCUMENTATION on EVERYTHING. (literally hobo instructions)