fax machines

[ScallViz]

Hello

I've been tasked with moving my Ricoh MFPs off of their POTS lines for faxing.

I was able to set up a fax extension in 3CX and put the details into the Ricoh.

We have 2 sip providers but only one (Telnyx) provides T38 service, so I put an outgoing rule to forces calls from the fax extension to use Telnyx.

I did some test faxes and none of them went through.

Using the Telnyx debug system, I can see the call succeeding until it's answered and then Telnyx sends a T38 invite:

v=0
o=FreeSWITCH 1683641169 1683641172 IN IP4 64.16.226.16
s=FreeSWITCH
c=IN IP4 64.16.226.16
t=0 0
m=image 26854 udptl t38
a=T38FaxVersion:0
a=T38MaxBitRate:14400
a=T38FaxFillBitRemoval
a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:2000
a=T38FaxMaatagram:400
a=T38FaxUdpEC:t38UDPRedundancy

It sends this 3 times and then sends a "bye" which the 3CX then acknowledges.

I've double checked the settings where I can find them and I do have T38 fallback to G711 enabled for incoming faxes from my other non-T38 compatible sip provider.

Are there any additional options I should choose for the Telnyx trunk to allow the T38 reinvite to go through?

The call shows up in the call log for 6 seconds and the following shows up in the activity log:
05/10/2023 9:53:18 AM - L:864.1[Fax:880] failed to create MSEP!

I did turn up the activity logging level and captured the whole process I'm just going through it now to see if there's anything I need to redact before sharing.

Thank you
-S

 

[ScallViz]

I looked through the activity log on Verbose and it showed most of the back and forth but didn't show anything about T38 or being reinvited with T38.

 

[YiannisH_3CX]

Hello @ScallViz

What did you use to connect the Ricoh to the PBX? You will need a T38 capable ATA device to do so. Connecting them directly will not work.

 

[ScallViz]

Hello @ScallViz

What did you use to connect the Ricoh to the PBX? You will need a T38 capable ATA device to do so. Connecting them directly will not work.

Thanks for the response.

The Ricoh units we have are native SIP/T.38 devices, so I would have assumed they would work without needing an ATA? It seems redundant to use an ATA on a device that supports T.38 internally? They are set up as Fax extensions in 3CX (not just user extensions)

The issue seems to be that the 3CX doesn't respond to the T.38 reinvite (it doesn't even show it in the logs?) when Telnyx sends it. Do I need to enable anything on the 3CX side for that?

Thanks
-S

 

[YiannisH_3CX]

Try to receive a fax to the email of a normal extension (or the fax server) and see if that works first. If inbound works you can then try outbound.
I am not sure how your devices are working so I cannot guarantee that it will work. You may need to run some packet captures to determine what the issue is.

 

[ScallViz]

Thanks. I did some deeper digging and there appears to be an auth issue between the ricoh and the 3CX even though the 3CX starts to initiate the call before it fails.

I've been looking at the PCAP in Wireshark and I've re-entered the credentials into the Ricoh to no avail. I'll keep on it and reach out to my Ricoh rep and see if I'm missing something.

Thanks