Any idea why I am getting this error when someone tries to send me a T38 Fax?
Maybe you have not allowed T.38 as acceptable codec 😉
You can try with “allow=all” in your sip.conf.
Am 22.05.2013 16:39, schrieb Andrew Colin:
488 not acceptable is due to codec error. Make sure you have right codec in place between the end points.
Am Donnerstag, den 23.05.2013, 20:48 +0200 schrieb Maximilian Grobecker:
No, T.38 is not a codec and so allow=all will not help.
To use T.38 You have to enable T.38 with “t38pt_udptl = yes” in sip.conf.
The reason, why You get a “488 Not Acceptable Here488 Not Acceptable Here”, is only detectable with a SIP Trace. There are many reasons e.g.
– Your asterisk version does not support T.38
– T.38 is not enabled (see above)
– T.38 is enabled, but not at the relevant peers (in most versions of asterisk there is only support for T.38 passthrough, so both peers have to support T.38)
– There are problems in the transmission and some peers wants to switch back to audio level and the other or asterisk is not willing to support this. The last reason may occur, if You have NAT and do not correctly forward the data ports of T.38 (UDPTL Ports).
Best way is to get a SIP Trace to analyse. If You provide one, You should also tell, which version of asterisk.