T.38 gw: V.17 call failing if far-end fails to train (FTT)

freeswitch / spandsp

SpanDSP is a low-level signal processing library that modulates and demodulates signals commonly used in telephony, such as the "noise" generated by a fax modem or DTMF touchpad.

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T.38 gw: V.17 call failing if far-end fails to train (FTT) #54

Closed lexxer3d closed 9 months ago

lexxer3d commented 1 year ago

Hi!

When t38_gateway on sender side receives FTT, the subsequent TCF is sent to far-end as v17-14400-short-training not as v17-14400-long-training. Also we should switch to V.21 since as per Figure 5-2a/T.30, (TSI)DCS should be repeated as well.

Spandsp log and suggested fix is attached. ftt.zip

coppice-git commented 10 months ago

I just committed the a change, more or less as suggested. Its weird that didn't show up before. I'll have to put some more tests in the test scripts to test the fix more thoroughly, but its clearly a basically correct thing to do.

lexxer3d commented 9 months ago

Fixed by commit 227b3126.