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Fax support on FPL?

PostPosted: 08/27/2020
by mh1983
Hi all, hope everyone's keeping safe and well during these strange times.

Lately, have had more of a need to send faxes instead of using physical mail to avoid surface contact, unnecessary trips, etc. Was wondering if faxing could technically work on FPL (last I read it wasn't officially supported, though i see mention of it here: https://support.fongo.com/hc/en-us/arti ... %20account.). We're still on the HT701, which I see has some fax-related config in it.

Any help is appreciated. Thanks!

Re: Fax support on FPL?

PostPosted: 08/27/2020
by Liptonbrisk
Although faxing isn't officially supported, FPL does work with T.38 fax protocol.

For Grandstream ATAs, use these settings found in the FXS Port tab:

1) Re-INVITE After Fax Tone Detected: Enabled
2) Fax Mode: T.38
3) Fax Tone Detection Mode: Caller or Callee
4) Use First Matching Vocoder in 200OK SDP: Yes
5) Preferred Vocoder: choice 1: PCMU
6) Disable Line Echo Canceller (LEC): Yes
7) Disable Call-Waiting: Yes
8) Disable Call-Waiting Tone: Yes (not sure if this needs to be disabled if #7 is disabled anyway, but the tone here is definitely bad for faxing)
a) I'm not sure if you also need to disable Call-Waiting Caller ID with #7 and #8 disabled, but disabling it wouldn't hurt for faxing. I don't have your ATA to test. Disable just in case.
9) On your fax machine or printer, set fax transmit or baud rate to 14,400. If that doesn't work, try 9600. If 14,400 works, you can try faster speeds.

I have faxed at 33600 successfully using FPL with an OBi202.

10) If you have problems, try changing Jitter Buffer Type to Fixed from Adaptive in your ATA.

Re: Fax support on FPL?

PostPosted: 08/27/2020
by mh1983
Very helpful as always, thank you!

Re: Fax support on FPL?

PostPosted: 08/27/2020
by Liptonbrisk
You're welcome!

Re: Fax support on FPL?

PostPosted: 01/05/2021
by mh1983
Happy New Year, all!

Sorry to bump an earlier thread, but am starting to look into this setup more earnestly. Any suggestions for USB fax modems? They seem to be readily available but want to make sure I get something that's compatible. Thanks in advance!

Re: Fax support on FPL?

PostPosted: 01/05/2021
by Liptonbrisk
mh1983 wrote: Any suggestions for USB fax modems?


Happy New Year!

I just use my multifuction laser printer to fax. I don't have any suggestions, sorry. Perhaps someone else does.

Re: Fax support on FPL?

PostPosted: 01/10/2021
by mh1983
Thanks as always! I'll take the plunge and check out a USB fax modem soon.

If I set up our main line as a fax, is there a way to continue to have the option to make calls on the line or can it only be one or the other?

Re: Fax support on FPL?

PostPosted: 01/10/2021
by Jake
Years ago we used to have a Fax printer on the main line. That didn't cause us any issues.
What we did find was we tended to receive more faxes than sending them so at one point we got a second FPL number and didn't actually connect anything to it, then just used that as a fax line. Any faxes coming into it would be saved as a pdf online so it didn't bother the main line at all.

It can be a bit hit and miss as to if faxes go through. Things might have changed but it seemed to go through better when things were all set on high quality, but seems counter intuitive but it seemed to work.

Re: Fax support on FPL?

PostPosted: 01/12/2021
by mh1983
Thanks for the insight, Jake! Appreciate it!

Re: Fax support on FPL?

PostPosted: 01/28/2021
by mh1983
Wow, this went a lot more smoothly than expected! Our HT701 is now hooked into a USB fax modem like this one: https://www.ebay.ca/itm/56K-USB-V-90-V- ... SwezVWzbTt. I configured the ATA according to Lipton's directions. I was just able to use an online fax service to send a fax and it received beautifully on my desktop that the modem is attached to. Very cool! Thanks again for the help!

Re: Fax support on FPL?

PostPosted: 01/30/2021
by Liptonbrisk
I'm glad it's working well for you.