[SIPForum-discussion] FAX Issue in VoIP

[Broussard, Dan]

I have found that G.711 does a better job than T.38

FAX devices that use V.34 to achieve 28800 bps and 36600 bps transmission rates are often referred to as Super Group 3 devices.  Customers serviced usually can achieve 28800 bps and 36600 bps transmission rates using G.711.  They cannot achieve these transmission rates using T.38.


From: discussion-bounces at sipforum.org [mailto:discussion-bounces at sipforum.org] On Behalf Of Brent Shaw
Sent: Thursday, September 09, 2010 2:14 PM
To: murali shankar; discussion at sipforum.org
Subject: Re: [SIPForum-discussion] FAX Issue in VoIP

The errors that you list make it look like you are not even getting a successful connection/negotiation. Do you actually connect, and then the failure occurs during transmission? If so, you might want to check the following settings:


t38 max-bps rate <value>
t38 max-buffer size (Had to adjust from default 200, to 262)
t38 max-datagram (Had to adjust from default 72, to 176)

Check the SDP offer when the T.38 session is initiated.

Your default values may be different

Brent

From: discussion-bounces at sipforum.org [mailto:discussion-bounces at sipforum.org] On Behalf Of murali shankar
Sent: Wednesday, September 08, 2010 8:28 PM
To: discussion at sipforum.org
Subject: [SIPForum-discussion] FAX Issue in VoIP

Dear All,

            Whenever am trying to send multiple pages in FAX over VoIP at a single attempt the FAX is getting failed .Whereas for the same number the FAX is going fine for single Paper.Can any one help me out?

Voip Gateway: Free Switch PBX.
Protocol: T.38
Codec: G.729A & G.711U
Baud rate: 9000 to 14400

Errors:
1. Busy Signal Detected.
2.No response to pps repeated 3 times.
3.Failed to train remote modem at 2400 BPS or minimum speed.


Please suggest.

Regards,
Murali
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