"res_rtp_asterisk.c: Don't know how to represent" when trying to fax on Asterisk v18. Worked on v16

[SoWhy]

Hi all,

I recently upgraded my Issabel v4 to v5 which included an upgrade from Asterisk 16.26.0 to 18.19. I imported all the settings, including the setup to send and receive faxes using Hylafax and everything is still configured exactly the same.

However, when I’m now trying to send a fax, I get

[2024-09-14 23:01:56] WARNING[14754][C-00000074] res_rtp_asterisk.c: Don’t know how to represent ‘’
[2024-09-14 23:01:56] WARNING[14754][C-00000074] res_rtp_asterisk.c: Don’t know how to represent ‘’

in my log file and the fax fails with

Sep 14 22:59:24.11: [14450]: MODEM READ ERROR: errno 5
Sep 14 22:59:24.11: [14450]: → [0:]
Sep 14 22:59:24.11: [14450]: MODEM
Sep 14 22:59:24.11: [14450]: COMREC invalid command received/no DIS or DTC
Sep 14 22:59:24.11: [14450]: SEND FAILED: JOB 11 DEST 081219028722 ERR COMREC invalid command received/no DIS or DTC
Sep 14 22:59:24.11: [14450]: ← [9:AT+FTH=3\r]
Sep 14 22:59:24.11: [14450]: MODEM WRITE ERROR: errno 5
Sep 14 22:59:24.11: [14450]: MODEM input buffering enabled
Sep 14 22:59:24.11: [14450]: MODEM setInputBuffering::tcgetattr: Input/output error
Sep 14 22:59:24.11: [14450]: MODEM tcsetattr: Input/output error
Sep 14 22:59:24.11: [14450]: ← [5:ATH0\r]
Sep 14 22:59:24.11: [14450]: MODEM WRITE ERROR: errno 5
Sep 14 22:59:24.11: [14450]: MODEM set DTR OFF
Sep 14 22:59:24.11: [14450]: MODEM set baud rate: 0 baud (flow control unchanged)
Sep 14 22:59:24.11: [14450]: MODEM setBaudRate::tcgetattr: Input/output error
Sep 14 22:59:24.11: [14450]: STATE CHANGE: SENDING → MODEMWAIT (timeout 5)

according to the HylaFax logfile. I tried the old install (which I still have backed up) and it works just fine.

Any ideas why v18 fails to send faxes while v16 works?

Receiving also doesn’t work but one problem at a time…

TIA
SoWhy

[penguinpbx]

That’s a lot of non-Asterisk stuff going there with such a major upgrade so hard to say where the issue is. Generally, faxing improves each release of Asterisk, have you looked in to T.38 ?

[SoWhy]

The posted error is the only difference afaict between v16 and v18. Not sure what you mean by looking in to T.38 though. t38pt_udptl=yes is set in SIP settings.