diff options
Diffstat (limited to 'configs/sip.conf.sample')
| -rw-r--r-- | configs/sip.conf.sample | 26 |
1 files changed, 18 insertions, 8 deletions
diff --git a/configs/sip.conf.sample b/configs/sip.conf.sample index 23c16979c..f32d60915 100644 --- a/configs/sip.conf.sample +++ b/configs/sip.conf.sample @@ -496,22 +496,32 @@ srvlookup=yes ; Enable DNS SRV lookups on outbound calls ;callcounter = yes ; Enable call counters on devices. This can be set per ; device too. -;----------------------------------------- T.38 FAX PASSTHROUGH SUPPORT ----------------------- +;----------------------------------------- T.38 FAX SUPPORT ---------------------------------- ; ; This setting is available in the [general] section as well as in device configurations. -; Setting this to yes, enables T.38 fax (UDPTL) passthrough on SIP to SIP calls, provided -; both parties have T38 support enabled in their Asterisk configuration -; This has to be enabled in the general section for all devices to work. You can then -; disable it on a per device basis. -; -; T.38 faxing only works in SIP to SIP calls. It defaults to off. +; Setting this to yes enables T.38 FAX (UDPTL) on SIP calls; it defaults to off. ; ; t38pt_udptl = yes ; Enables T.38 with FEC error correction. ; t38pt_udptl = yes,fec ; Enables T.38 with FEC error correction. ; t38pt_udptl = yes,redundancy ; Enables T.38 with redundancy error correction. ; t38pt_udptl = yes,none ; Enables T.38 with no error correction. ; -; Faxs Detect will cause the SIP channel to jump to the 'fax' extension (if it exists) +; In some cases, T.38 endpoints will provide a T38FaxMaxDatagram value (during T.38 setup) that +; is based on an incorrect interpretation of the T.38 recommendation, and results in failures +; because Asterisk does not believe it can send T.38 packets of a reasonable size to that +; endpoint (Cisco media gateways are one example of this situation). In these cases, during a +; T.38 call you will see warning messages on the console/in the logs from the Asterisk UDPTL +; stack complaining about lack of buffer space to send T.38 FAX packets. If this occurs, you +; can set an override (globally, or on a per-device basis) to make Asterisk ignore the +; T38FaxMaxDatagram value specified by the other endpoint, and use a configured value instead. +; This can be done by appending 'maxdatagram=<value>' to the t38pt_udptl configuration option, +; like this: +; +; t38pt_udptl = yes,fec,maxdatagram=400 ; Enables T.38 with FEC error correction and overrides +; ; the other endpoint's provided value to assume we can +; ; send 400 byte T.38 FAX packets to it. +; +; FAX detection will cause the SIP channel to jump to the 'fax' extension (if it exists) ; after T.38 is successfully negotiated. ; ; faxdetect = yes ; Default false |