I recently configured T.38 on Asterisk 10.4.2. When I send the fax to
Asterisk, it gives the errors as listed below;
WARNING: app_fax.c:442 transmit_audio: channel
‘SIP/192.168.1.69-00000000’ refused to negotiate T.38
WARNING: app_fax.c:174 span_message: WARNING T.30 ECM carrier not
As in sip.conf the configuration is listed below;
t38pt_udptl = yes,fec,maxdatagram=400
faxdetect = t38
And the rest are the standard configuration.
Please advise to resolve this issue.
Does your VoIP provider support t.38?
Sent from my iPad
Here is my setup;
Fax machine -> PSTN -> Cisco Voice GW -> IP cloud -> Asterisk. As on Cisco
Voice GW, T.38 fax already configured on SIP protocol.
Apparently your configuration of the ‘Cisco Voice GW’ was not
successful, as it refused to accept a re-INVITE from Asterisk that
wanted to switch the SIP channel to T.38 mode.
The configuration I did in Cisco Voice GW is listed below;
dial-peer voice 2852 voip
description Incoming Fax Calls to Asterisk
session protocol sipv2
session target ipv4:192.168.1.69
fax protocol t38 ls-redundancy 0 hs-redundancy 0 fallback none
Please advise to overcome this warning.