Problem Receiving an e-Fax from a PC

[CiscoRookie]

Our phone system is Cisco VoIP. My problem is with a particular fax machine. The user complains that her fax won't receive from a customer sending an e-fax via pc. Her customer says the e-fax appears to have sent properly - they bring in the send confirmation sheet to prove it, yet the fax doesn't receive the transmission. The user says the fax sounds as if it's receiving, then it stops. We have 73 faxes over 6 VG224s, and we just got them working properly a few months ago. This required a few changes to the configs on our gateways. I am loathe to make any additional programming changes that would affect the entire enterprise for what sounds like a one user issue. Does anyone have any suggestions?

 

[trvlr1]

Do your DID numbers go directly in to the VoIP system, or do they route through other systems and then in to the VoIP? We had an issue where we had to move a few fax DID's from TDM systems to VoIP, initially we routed the calls over TIE lines in to the VoIP, but found that when using PC/Server based faxes to call the VoIP fax, they gave similar results to what you are describing, even though standard fax machines seemed to have no issues. The solution was to move the DID's to lines going directly in to the VoIP system, this cured the problem.

 

[CiscoRookie]

Our DIDs are routed through specific PRI circuits directly to our VoIP system, to the best of my knowledge. We switched from an Avaya Definity to the Cisco VoIP system. I don't believe we were routed through any other devices before the switch, though I can certainly check on that. Thanks for the tip, I'll let you know if I discover anything.

 

[TouchToneTommy]

Have the sender fax to one of the other 72 fax machines, and see if it comes through. If not, the problem is on the sender's end.

 

[donb01]

Have you tried swapping that fax machine with another one that you know is working? I'm wondering if this might be an older fax machine and the person who is sending the fax is using a newer protocol that it doesn't support.

Group3 fax protocol has been around for ages, so I doubt it's that, but there is a Group4 protocol out there that has different compression and I could see it might be possible for someone sending from a PC to have something set wrong.

I have had people complain to me that they could not send faxes to my machines from their Vonage or other "magic jack" type of provider using their PCs, and they swear that they don't have problems sending their faxes to other places. After I proved there was nothing wrong with my fax I made the assumption that it had something to do with the fact that my calls come in on PRI (digital) phone lines and the other locations just had plain old analog lines. The people could not get their faxes to go to our fax machines but they were received and processed by our RightFax server just fine, so I ruled out a PRI issue. From there I looked at the session logs and discovered they had their PC fax software configured to send out Group4. After they changed the setting it fixed the problem for me.

Just another thing to think about if the DID routing idea doesn't pan out...

 

[CiscoRookie]

The user was kind enough to ask her customer to send an e-fax to another machine. It worked. What's more, the other fax machine is the SAME model as the one having the problem: Brother Intellifax 4750e. I've printed out the user settings for each machine, but these are basic settings that don't go into ecm or speed. The only difference was the ring delay, which is 4 rings on the working fax and 0 rings on the faulty fax. Still investigating...

 

[Sympology]

What CODEC is being used to get to these faxes? G711? are you using T38?
How is the fax attached? Via a ATA? If so is the config the same?

Robert Wilensky:
We've all heard that a million monkeys banging on a million typewriters will eventually reproduce the entire works of Shakespeare. Now, thanks to the Internet, we know this is not true.

 

[donb01]

The ring delay might be giving the connection a chance to settle down before the fax answers and tries to handshake - wouldn't hurt to change that for fun.

We use Brother 2850's. I never did hear if the last problem got solved - I told the person to call Vonage and ask because I htought you had to pay extra to be able to do fax transmissions on their system and they may have a different system profile for a fax user. The only difference I could see in my situation is the fax that wasn't working was on a PRI line and the ones that weren't having any problems were on POTS lines.

If you figure it out be sure to post back because I would be interested in knowing how you resolved it.

Thanks

 

[Munz]

I just had a thought with the problem described here. As a fax is sent via the Telco's network an echo cancelling device is removed from the call for fax and data transmissions. People don't like echo, because it causes us to pause and repeat while speaking, however, machines don't like echo cancellers because it distorts the real data stream into something different. The sending fax should be sending tones during call setup, and, before the receiving fax answers so that the echo cancellers can be dropped from the call. PC based fax equipment behaves different to fax machines. Maybe there is a setting that can be adjusted to fix the problem, but the best way to check for this is to monitor the call with a test phone (ie buttinski) to see if the sending fax is sending tones while the call is still being "setup".
The other problem is some fax models will never ever connect to some other fax models. Just won't. Not many, but some.

Regards, Munz

 

[CiscoRookie]

Since the fax that can receive e-faxes is the same model as the one having difficulty receiving e-faxes, and the only difference between the two was the incoming fax rings, I changed the number of rings to 4 (identical to the fax that works). It made no difference. This fax will still not receive an e-fax.
I did notice that the 2 fax machines are on different VG-224s, so I moved the faulty fax to a port on the other VG-224. I'm waiting for feedback from the user.....
I have not had a chance to compare the running configs on the two VG-224s. If the fax now receives e-faxes, then I will have to compare and make any necessary changes. Since we just recently got our fax machines using the VG-224s working consistently, I am loathe to make config changes without some concrete proof that the change will be beneficial.

 

[donb01]

I haven't ever thought of firmware in a fax machine, but I suppose you could also have 2 identical model fax machines but one is newer than the other and has newer firmware. That's way off the wall in left field, but if it would be the case I would have no idea how to do a firmware upgrade unless you have to change a chip....