MODEMS don't work with PRI over AT&T Flex 3

[bobertb]

[highlight #FCE94F]Once you switch over you IpO (and BCM for that matter), any applications using a MODEM will NOT work.[/highlight]
Not sure I would expect any different outcome with other provider's offerings.
I'm hoping someone replies to this and says I'm full of it and has a solution

This is a major headache that you should nip in the bud as soon as you get wind of a customer going this route.

NOTE: This is AT&T router handing off PRI to IpO...not SIP
If you monitor the connection with a Butt Set and use, say, ProComm, this is what happens:
[ul]
[li]ProComm dials out[/li]

http://www.tek-tips.com/threadminder.cfm?pid=940

[li]Far end MODEM answers[/li]
[li]You hear 1/2 second of data[/li]
[li]Procom says "Disconnected" and tries call again.[/li]
[/ul]

This happened to our corporate office when we switched from Time Warner PRI's. We didn't find out right away (like 2 weeks) because our modem needs are sporatic.
I opened a ticket with AT&T. They played around with it for 1.5 weeks. They monkeyed around with router settings, like setting up for G711.
No luck. I've been on vacation. I think ticket is still open.
We are in the process of ordering some 1MB's.

Today I am at another customer that switched to AT&T Flex a year ago.
It is a BCM400. They don't use modems, so I cranked up ProComm for a test.
SAME problem as on the IpO

I have not had any customer complaints regarding FAXING.
I have not tested CREDIT CARD terminals yet, but I sure want to.
I haven't tried this at any CS1000 sites yet.

Also since we upgraded, there are certain IVR systems we can't break into menus with DTMF.
One is an Verizon 800 number we frequently use.
It does work with an analog set as you can push DTMF out for as long as you press the keys.

 

[bobertb]

So I contacted US Robotics to get their take and this issue.

They responded with this:

> We do not publish telephone line requirements since there are too many variations in subscriber loops throughout the world. Since modems are adaptive devices, they are designed to handle most line conditions.The general characteristics that make a line feasible for modem traffic are:
>
> Bandwidth: 300 to 3000Hz
> SNR: 32db or greater
>
> Ultimately, the problem you are facing is not likely to be with electrical characteristics of the line between the modem and the PBX adapter. The issue most properly lies in the transport of modem audio packets. Once again, we can only provide general characteristics that will enhance transport of modem audio.
>
> Uncompressed g.711 codec
> No VAD or CNG
> Near zero packet delay (QoS)
>
> If possible, ask your provider if they can implement/provide T.38 for faxing needs.

 

[amriddle01]

Near zero packet delay" ....never going to happen