sundance-communications.com/forum Forums General General Telephone & Systems Information FAX problems

This happens to people who eat lobsters that should be left in the ocean to enjoy their crawling around.

Vegeburgers make all your problems go away and increase your IQ.

Do you know how much warmer it is in LA in January than in Fort Kent or Caribou, I do and I like it. In Maine you can't get to there from here, and in California you treat things like this with a very mellow attitude.

OK, for the real advice, see if the fax is set to answer on the first ring (preferable) or more rings (less preferable like eating poor little lobsters.)

Not sure if you're dealing with a LEC or CLEC.

If you have VoIP, the fax line (as well as computer modem lines & alarm system lines) will have to be provisioned differently. You can cut voice to 32K and the human ear can't tell any difference... but those fax machines do.

Same thing applies if you're using a VoATM or VoDSL technology. One of the CLEC's in the OK/KS/TX area was using that technology, served out of Lucent and/or Verilink Channelbanks.

If you're dealing with T1, slips or bit errors could also cause this problem.

this is driving me nuts :bang:

All 3 businesses are small with POT lines, all have dedicated FAX lines. The problem started Oct 17, for one of them. They do daily reports and it is seems to be just one company that can't send to them my office is just around the corner from them and their vendor can FAX to me fine. Could there be a certain FAX protcol that is being blocked? This is a new account and problem started about 2 weeks after new system was installed so we all know who the finger is pointing at.

By dedicated line I am assuming you mean from the LEC RJ-21X handoff directly to the fax machine, and not through the phone system or a line sharing box.

Can they receive any faxes? local (within the same wire center), local (from a different wire center), local (possibly from a different LEC), or LD?

We have encountered a problem with interconnect trunks (between my CLEC employer & the ILEC at the tandem) where a misoption caused us quite a bit of grief. So long as it was within our switch everything was fine, but to a different NXX on those trunks caused problems. This was a real fun one to find.

Anything they have in common - same LD company, same rate center, same LEC/CLEC, trouble with same NPA faxing to them, calling party has same LD carrier?

Have you tried to disable error correction if it is available on their fax machines?

Have you tried using the fax machine on a different line, just to rule out their current fax line?

Kyle
Yes line is direct to FAX machine

They can receive from lots of places, local, in state and out of state. One customer has only one location that they know of that can't FAX they are located in Mass. Only get a black line across top of page sometimes they get partial page. This vendor sent to my office ok and I'm located around the courer on next block from customer. The second customer can get several from all over but have a few in state LD that can't get through. Their FAX will answer take a long time then say receiving then cut off, error report says it tries 9600,7200,4800,2400 then disconnects. Tried disabling error on this machine no effect also tried plugging into main line still had same problem.

Since customer #1 is having problems with (hopefully) only one location faxing to them, have you tried contacting someone at the location in Massachusetts? Is it possible they recently switched LD companies? Can they send a fax to you? Can they disable the error correction on their fax machine?

Would it be possible to have companies failing to company #2 send test faxes to company #1 or to you?

Kyle got your PM thanks

After trying several things I found that most Faxes would go through. The places that couldn't fax to customers could fax to my office. We are all with in same LEC. The problem seemed to be with only a few places and most of them would act the same. FAX would answer call, display would show receiving, then error out or part of page would come through. Our LEC is also the internet ISP for the area and they have been experiencing problems with a upgrade. I thought it maybe an issue with calls being routed Voip from LD carrier and have set on this for a week. Customer #1 + 2 are getting all Faxes ok now, haven't heard back from #3
My guess is it was something with the phone co.

The Problem was T1 line coding. There was a mismatch between a co switch and a transport mux. one unit was set to AMI the other to B8ZS. B8ZS stands for Binary 8 Zero Substitution. DATA (like from a FAX Machine) is rich in consecutive Zeros in a T1. Units otioned for B8ZS Substitute 8 zero bits for 8 bits with 4 zero bits and 4 one bits with a special pattern including bipolar violations. When a unit optioned for AMI recieves this pattern it does not replace the 4 one bits with zeros thus changing the signal.

Phone traffic between central offices do not take the same pattern. Switches like the 1AESS and the 5ESS hunt outgoing idle trunks from one end of the list of trunks and the office at the other end hunts from the other end of the list of trunks. Its like a toll boths on a large toll road goint into a city. When cars come to the boths they use the boths on the right and aposing traffic uses the boths on the left. This keeps cars and telepone calls from runing into each other. If you place nails in front of the boths going into town only people going into town will get a flat. Thats why the FAX failures were only one way.

Yup. I got this explanation once from someone I've forgotten and can't give credit to. No reason this can't happen elswhere besides customer T1.

You have a T1 into you PBX, voice calls are not a problem, but you can’t send a FAX. The T1 that you are leasing from the LEC is terminated into a Digital Crossconnect System (DSC) at the CO. The LEC uses the DCS to connect the T1 channels to CO carrier channel banks with FXO channel units. This takes the digital channels to analog to connect to the CO switch ports (POTS).
T1 coding has two options ESF/SF (SF is listed as D4 on some test sets) B8ZS/AMI. If the ESF/SF options at each end of a T1 do not match the system will not sync up and the T1 will not work at all. T1 transmission requires at lease a 17% ones density to keep sync. G.711 coding of voice is rich in ones. Data can have a high number of zeros causing a carrier system to have a low ones density. To overcome this B8ZS was introduced. Any time a channel has all zeros; Binary 8 Zero Substitution (B8ZS) will replace the channel with 4 bits with 2 bipolar violations. When the equipment at the other end of the T1 detects the B8ZS code the equipment will replace the four one bits with all zeros.
B8ZS/AMI option must match at both ends of the CO DCS to carrier channel bank. When the DCS is optioned B8ZS and the channel bank is optioned AMI, voice will work ok but Fax’s will fail. This is difficult for the CO to find. If your PBX lines are spit between banks and only one is optioned wrong, sometimes you can send a FX sometimes you can’t, depending on witch co line you uses.

-Hal

And, in the event you need to convert an ESF/B8ZS T1 to AMI/D4 at the customer premise, some CSU/DSU's allow you the option.

Most everyone uses ESF/B8ZS T1's these days because of data. We've encountered older PBX's that need AMI/D4, and had to pull the above maneuver to fix it.