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T38

Robert Craig
Participant
Participant

My ITSP only supports G711 Pass-Through for faxing. I want to experiment with T38 internally. Can I implement T38 on the inside of my network by applying it to the dial-peer going to my CUCM, and keep pass-through on the dial-peer going to my ITSP? I can't find anything saying that T38 has to be carried all the way through or it can be changed at a certain hop. Any help is appreciated. Thanks!                  

1 ACCEPTED SOLUTION

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Correct assuming you configure a fallback option on the gateway/CUBE.

voice service voip

fax protocol t38 version 0 ls-redundancy 0 hs-redundancy 0 fallback pass-through g711ulaw

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5 REPLIES 5

Steven Griffin
Enthusiast
Enthusiast

Robert,

The T.38 protocol is, for all intents and purposes, a codec.  As I understand it there currently* isn't a transcoder or MTP that can terminate a T.38 call and replay it as a G.711 call when doing IP to IP calls.  Thus the answer is, currently*, no.

-Steven

* Currently = IOS 15.1(4)M5

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OK, so more than likely if I sent T38 towards the internal side, the end fax machine will just utilize pass through because there won't be a terminating device/gateway accepting or offering T38. I spoke to my provider and he is having the same problem. No one all the way up the line that will carry T38. Thanks for your help though.

Correct assuming you configure a fallback option on the gateway/CUBE.

voice service voip

fax protocol t38 version 0 ls-redundancy 0 hs-redundancy 0 fallback pass-through g711ulaw

Please remember to rate helpful responses and identify helpful or correct answers.

Yup, thats what I did and it did exactly that. I am experimenting with Flowroute as we speak. They support T.38 throughout their network. Thanks for the tip!

Hi Robert,

 

Would you mind reaching out to me to discuss your success/failures with T.38 faxing and flowroute?  We have a fax upgrade project and I'm looking at various options to move away from the traditional 1FB - analog fax machine model.

 

Thanks,

 

Amir

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