T.38 and Faxing

I’m trying to make an informed decision on replacing our PRI with a bunch of SIP trunks. Now, according to our provider, these sip trunks a) are separate bandwidth from our internet, and b) support T.38 faxing.

We receive about 2000 fax pages a week. We send out about 400-500.

We’re currently using HylaFax for both sending and receiving/routing. It’s working well, with 8 IAX modems and <1% failure.

Thoughts? Do’s and Don’ts? Has anyone had experience with the T.38 protocol? Do I dare try to do that many faxes over SIP?

I’d love to hear someone’s experiences with faxing.

Thank you!

I have several servers doing way more than that amount of FAX traffic using Hylafax, you can increase the reliablity by adding t38modems to the mix, thus eliminating the need for Asterisk, and using a “true” t38 VSP. FlowRoute comes to mind, but there are others.

T38fax.com and Flowroute both work well for T38. Im pretty sure the T38fax guys built hyla fax in the day. I could be wrong. I dont use hylafax just standard freepbx with some udptl config adjustments and t38 settings. Even works fine with ATAs as long as the fax can be set to 14400 with the right ata settings of course.

Always test it out before you port everything though.

Provider sounds like ISP should hook you up with a test sip trunk to try out.

We made a decision. The vendor is giving us a nice internet pipe and two “true” PRI’s (over fiber, but it’s still real PRIs).

Not going to do faxing over SIP if there’s any way I can avoid it (and this avoids it).

1 Like

This topic was automatically closed 7 days after the last reply. New replies are no longer allowed.