Problems sending fax's over T1

[jmchugh79]

I am using a Dialogic CPI400B2 fax board on 3 servers. We are sending 4000+ fax's a day on this system but keep having problems sending to a handful of fax numbers. They claim they get fax's from many other sites with no problem, only have problems with ours. I created a test fax and sent it to our test fax machine and then to their machine. When sending to theirs I see a Dialogic error 3268 which indicates a bad connection or echo.
We have isoloted the problem but the solution is a bit tougher. This site has 36 fax lines coming out of 3 fax cards. Once it gets to the PBX (which is a Meridian Option 11) the calls then go out one of two T1 lines. These are provided by Verizon and are called Flexpath lines. They have been tested and re-tested by Verizon and they claim they are clean. Yet we still get a few dozen of these 3268 errors each day, and even more who are getting poor quality fax's. So as a test we took the T1's out of service and switched over to some copper lines (standard analog Verizon lines) we also have on that PBX (intended for backup only) and the calls all started going through perfectly.
Anybody seen this before? Should there be any difference whether it goes out copper or T1? Our PBX folks say there are only one ot two adjustments they can make to T1 circuits and they dont seem to make any difference. Any suggestions?
Thanks!!
Jim

 

[johnpoole]

very strange, fax will work better on copper because it's way slower.. doyou have faxa in class on the analog sets? you could drop the gain on your digital trunks by changing the class from vnl and make adjustments on the switch

john poole
bellsouth business
columbia,sc

 

[jmchugh79]

We have dropped the gain a few times and it seemed to improve a little, one customer that never went thru went thru sometimes. I will check with the switch folks to see if they have the fax class set on the analog piece.
We are also going to have Verizon run some tests to see if there is any timeing problems.

 

[johnpoole]

that might help, the faxa will help. i usually try to correct problems on the switch side instead of the carrier side, seems that when they get on a problem it either takes to long or they make changes that you are not aware of and they cause other issues.. with internal changes you can make a change and test it then if needed change it back..

john poole
bellsouth business
columbia,sc

 

[jgideon]

Is the long distance carrier on the copper trunks the same as the long distance carrier on the flex paths? Most of the 'intermittant' fax problems I've seen end up being trunk issues on the far-end, or with the LD carrier, especially if the local loop test clean, and you don't have clocking errors, etc.

 

[jmchugh79]

Long distance is the same on both, but its even local calls that are having problems.

 

[jgideon]

well, at least you've checked. There are others here better equipped to speak directly to the switch questions...

I have run into some flat-out incompatibilities between fax products, but never on 'server' class hardware, just individual faxmodems.