Take a look at https://wiki.freeswitch.org/wiki/Mod_spandsp#t38_gateway Probably you need to disable the t38 on one of the sides. On Mon, Jan 16, 2017 at 4:43 AM, Tristan Dean <tristan@mocha.net.nz> wrote:
Hi All
I am having trouble on a new FreeSWITCH-based SBC we’ve built. We are going through some SBCs and upgrading them. In this case, we are upgrading an old SBC running: 1.4.15 64bit built from source.
The new version is running on Debian 8.3 (AMD64) Stable with the packaged version of FreeSWITCH: 1.6.14 -23-e460bf8 64bit
We are tying this in with a hardware swap, so the 1.6.14-23 box is new.
We have a few instances where our upstream carrier presents us with a SDP which contains:
m=image 56594 udptl t38
a=T38FaxUdpEC:t38UDPRedundancy
a=T38FaxRateManagement:transferredTCF
Historically (version 1.4.15) these seem to be ignored and FreeSWITCH passes the call out obeying the absolute_codec_string set during bridge. Transcoding is allowed and when negotiating a codec with the carrier, these parameters were ignored and G.711a was usually negotiated on both legs.
On the new platform, FreeSWITCH seems to be attempting to parse these and negotiate T.38. I am certain that it is something silly that I’m doing wrong, but can’t find it and would welcome others’ thoughts. What have I missed? Has anyone seen this before? I have tried t38_passthru=true to no avail.
I can’t set proxy_media=true or bypass_media=true as we need FreeSWITCH to shield other devices from the SDP parameters above.
Most of the configuration is stored in a database and returned to FreeSWITCH using mod_xml_curl. I have pasted some configuration excerpts, SIP messages and logs in: https://pastebin.freeswitch.org/view/de059ffc
Please let me know if there is any other information you need from me.
Many thanks in advance for your assistance.
Tristan
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