Faxing over voip

[Newth]

What setting do i change on fax machines to make it work better over SIP trunks voip ?

 

[Billz66]

slow it down as much as you can

If I never did anything I'd never done before , I'd never do anything.....

 

[curlycord]

It sometimes helps to include what Phone System or SIP device or Fax machine or all the above.

-Changing the Transmission speed can help indeed....9600 baud or lower.
-Also try disabling ECM on the Fax.

-I use an ATA on a Nortel BCM and had to change the Fax Transport from T.38 to G.711 on the BCM.
G.711 is not compressed so works better for analog transmission.




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[Newth]

Its a NEC SL1100 /SIP trunks using MyNetFone as the SIP provider.

 

[curlycord]

Are you sure?
Look at your other post where you say it's an SV8100

And did you try Belvedere's settings?




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[SteveBUK]

Hi, as curlycord as suggested - Use baud rate of 9600 on the fax machine and ensure that the codec on the SIP trks are G.711 only
Don't use T38 or any complex codecs on the SIP trks.
Regards Steve

 

[sbcsu]

I have never found it to work correctly so I normally reserve an analog line or an ISDN circuit just for Faxes

 

[curlycord]

Newthe update please and thanks.

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[intrigrant]

I always set faxes to use G771 FoIP protocol and it is never a issue (i think) as faxing is hardly used in the civilised world(Western Europe).
We have fax2email, secure email and a lot more social media resources to communicate with.
In fact in the most offices here have no physical fax machine at all.

 

[Newth]

Changed setting on fax machine to 9600, disabled ECM.
Changed setting on NEC SV8100 to t.38 protocol and speed to 9600.
Still having problems with fax loosing parts of the text and distorting other parts.
In an area of Australia where they are fazing out PSTN and ISDN.
So I have to use VoIP.
Regards Dave.

 

[Billz66]

t 38 will only work if its supported on all devices in the IP part of the pipe
probably better chance of using g711 , a lot of carriers dont support t38

If I never did anything I'd never done before , I'd never do anything.....

 

[thepfy]

Might be worth checking the T.38 version you are using and what the other end is configured to.
We had some problems with faxes internally when we moved the PRI from our legacy switch to a Cisco CUBE.
The Legacy switch was expecting T.38 version 3, so once Cisco was set to use version 3 the issues disappear.

Most of our incoming calls arrive via Vodafone SIP and we aren't have any issues with faxes. I would have heard if we did.