I have a customer with a 500 cabinet. PRI 23ipx. 8SLS card. They have 5 fax machines going thru the system. No POTS lines on site at all. Has been working fine for years and now suddenly all faxes are failing. I swapped the 8SLS card with another and also moved to another slot. I have re-seated PRI and power cycled system. Cbeyond (telco) swears it is not on their end. The see no errors and when the fax fails they say they see "normal clearing". I have not swapped the PRI card yet as I don't have 1 in stock. Hate to spend the money only to find out it wasn't that, but I realize I may have to.

DIDBG shows no errors. Sync is good (0,4). No alarms.

I have an efax in my office. While on site today I tried a bunch of faxes from different machines. Most faxes would come into my email box saying 0 pages received. Some of them I would get about 1/8 of the page and then it cut off. Butt set on the line works fine for calling with no noise on the line that I can hear. Can have long conversation with out it ever dropping call. The customer is having no problems at all with dropped calls on the digital sets that are using the PRI as well.

Another issue is the modem. I have really poor connection when I connect remotely. A lot of times it won't connect at all. Was never a problem in the past.

Any ideas?

It's Cbeyond. Another VOIP carrier that has these issues all the time when the push updates. Just went through this with a customer same issue. Always the pbx...and usually never is.

Yep, it is definitely CBeyond and it can't be fixed. They've even told us so. In this market, they won't provide any guarantee that faxes, modems or alarm systems will work with their service. This is due to the magic of VOIP.

You can try turning off ECM on all of the fax machines and turning the baud rate down to 9600.

regarding the fax problem. Does the 500 have a PRI for your lines? If so tell your local phone company to provide extra bandwidth on incoming calls when they see a line going to XXX-XXXXXXXX. And also on out going calls from the fax you need to create a ALT_ID of the DID number of that single line port and assign it in slt definitions so when the phone company see's you fax machine dialing out, they also allow additional automatic bandwidth for out going. Of course a superG3 fax machine should be used but not necessary

Nobody mentioned the need for a CSU. Having a CSU installed is imperative to making this work. If you don't have a CSU you will experience the problems as described.

Cisco iAds have csu built in and not required.