Best Practices for Fax over G.711U

[iamtheari]

We are one of those unlucky businesses that has to be able to send and receive faxes, because we often deal with businesses that do not trust e-mail and can't wait for mail (insurance claims departments). Our telco informs me that their fiber equipment carries all analog lines with G.711U encoding. Our fax line worked fine when it was carried that way.

I am trying to get bidirectional faxing working through 3CX so we can use our SIP trunk rather than paying for an additional "analog" phone line that will just be encoded as G.711U a few feet away from our equipment. Our telco says they could try to provision T.38 but they don't have much experience with it. So I am trying to use G.711U as the path of least resistance.

I got a Patton SN102 for this purpose. (I chose it because it has two ethernet ports and I wanted to daisy-chain it with the network port on the MFP that it delivers a fax line to, but that actually didn't work because the SN102 wants to be a router, not a switch.) I am finding that it isn't reliable enough for faxes. I don't know if it's due to non-optimal settings on 3CX or on the SN102, or if the SN102 just isn't up to the task. Sometimes faxes fail to send or receive, and received faxes always have missing lines. Sent faxes seem to work better than received as far as quality goes.

What have others had luck doing for sending and receiving faxes? I don't mind buying a new ATA as the SN102 wasn't expensive, but I don't like to spend money if it won't actually help.

 

[sbrammer]

We started out using Pattons, then switched over to Grandstream because a few of the Pattons we were using were not supported (4118's, which we also had a few 4114, which were supported). They would work, then don't work. Or i would hear nothing, so i assumed faxing was working, then all of a sudden i would get an email that said faxes haven't worked in a while....

We then were using the Grandstreams HT814\818, and still were having issues. So we looked into going with a online Fax service, but in the end, we surveyed who still uses\needs to use faxes around our college. We dropped our physical fax machines by 1/2, and converted four fax lines back to POTS lines. A couple of more fax numbers are being forwarded to one of the POTS lines. Moving them back to POTS line ended a couple of years of battling with issues.

At the time, our SIP provider didn't do t.38, so we had to do g.711 for faxes. We also did try the fax server within 3cx, but for whatever reason, people didn't like that option, so it was nixed.

I hate to say this, but depending on how many fax machines you have, might be better off, going to POTS lines. However if you do get it working and it's reliable, then congrats.

 

[iamtheari]

We have one fax machine. We use it probably once per week. But when we use it, it's the only option. We can't use an online fax service because our phone numbers aren't portable.

If our POTS lines were copper, I wouldn't be so confused by the problem. But since our POTS lines are actually G.711U/RTP over fiber (and probably signaled with SIP), it should work just as well through our own ATA as through the telco's box.

It sounds like you didn't have any better luck with the Grandstream HT814/HT818 than you did with the Patton 4114/4118. So that means I can probably take the Grandstream HT801 out of my shopping cart and keep researching.

 

[sbrammer]

The other issue we had was our SIP provider was non-supported provider. But just recently switched to a supported provider in the last week. So i might not through out the Grandstreams quite yet, but that's up to you.

 

[cobaltit]

There's several threads on this. FoIP is best effort. As a 3CX partner and SIP trunking provider we don't recommend G.711/T.38 faxing. If your faxes absolutely must work, you get a true POTS line. The next best option (and what we do most of the time) is use a HTTPS fax adapter on our service that eliminates the whole G.711/T.38 discussion and just works. I've had good luck with incoming faxes to 3CX but faxing over a ATA is kinda like doing STUN without port forwarding. It works until it doesn't and it's not worth the time spent troubleshooting.