Strange Problem with Faxing

Hello Community,

By one of our customers happened a strange thing with faxing. Maybe someone can help…

When i installed the FAX Adapter (Cisco SPA112), i sent some test FAX and everything worked.
The customer sends Fax everyday to the same number which works perfect.

Now the strange thing…
The customer has also other companies where he sends Fax only sometimes. The Company accepts the FAX and the customer got an OK, that the fax was sent successfully.

But the receivers say they dont got any fax. :frowning:. They tried it more often but the Fax did not come over. But the FAX machine (It is a Brother Fax) everytime has successfully sent the fax.

So i said to the customer he should send us a Fax, but this works everytime. Only with the other companies they dont come over. The customer sends fax over years to them, and this worked in the past before switching to Voip.

I dont know what this can be the problem. Maybe it helps to try a Grandstream Adapter instead of the Cisco?

is the other company using fax to email? perhaps someone is receiving the fax but via email.

One company has FAX to email, the other company where it also does not work also has a Simple Fax machine. But the customer also called the companies “Hey i send you a Fax now…” but they say, sorry i did not reveive anything, i can hear it “BEEEEP BEEEP” but it prints nothing…

Our Company has FAX to Mail (FreePBX) and we reveive all Faxes.

The problem is last month before i installed them a VOIP Solution it worked.

i would check the log files on both the receiving fax machine as well as on the ata. if the receiving fax is beeping it might not be answering the call. is the receiving fax machine also attached to an ata?

One receiving FAX is on an ATA, answers the call and the customer has a Printed sheet with “FAX SENT SUCCESSFULLY”.
The other customer also has VOIP. Fax sent successfully, but after a call to them, they said, no sorry, there is no fax in our INBOX from you.

Is it possible that the fax data is being sent over one port and the receiver is looking for it on another port?
Check this with Wireshark while sending a fax, and then look at the call to see which ports are used.

when you say the other customer has VOIP, but explain what you mean. if they are using something like EFax, or vfax from vitelity, then you need to know that there will be a delay on the receiving end after the sender has received the “successfully send” message. Or are you running it through the PBX? i would also ask them to check their junk/spam mailbox

Oh FAX Hell - I know the well!

First things first, on any Brother machine, turn off the Super-G3 on the Sending FAX - FAX through Asterisk is very reliable right up to 14.4 - Beyond that and you will have LOTS of failures. Make sure all your devices are capped out at 14.4.

Second, decide if you are going to use T.38 and either make sure it is end to end (ATA, Asterisk, SIP Carrier) or not at all (Turned off on the ATA, NOT enabled on Asterisk, not offered or received by the Carrier) - a mix of T.38 enablement in some places but not others can cause this disappearance.

Finally, I am with the above Posters - I bet the FAX IS getting received and being shuttled off somewhere.

Good Luck.