Faxing Via SIP

[jmlee]

We have calling provided by a local SIP provider. We have had great success with the voice calling via this provder but have run into issues with Faxing.

We have Tried both G711 and G729 compression with the same results... call goes out, the fax tone on the other end is heard fax machine starts, after about 15 seconds the IPO says "call terminated by destination".

we are running IPO412 with software version 5.0

 

[Bas1234]

Try to play with the ECM settings on the FAX machine on/off
Also SIP does not allow a faster modem speed than 14k4 unless your provider supports T.38.
For the IPO to suppport T.38 you need to have the latest 5.0.22 firmware. You need to put the analog port on FAX and add a shortcode N/Dial Fax/N/ARS.
Also reinvite supported need to be ticked on the sip line to make it work.

But first try to play with ECM and setting the incomming/outgoing speed of the fax to 9600baud this works best.

___________________________________________
It works! Now if only I could remember what I did...

Dain Bramaged
___________________________________________

 

[jmlee]

BAS the ECM settings? Where are those?

 

[Bas1234]

In the FAX machine ECM = Error correction mode.

___________________________________________
It works! Now if only I could remember what I did...

Dain Bramaged
___________________________________________

 

[jmlee]

bas1234, we don't have T.38 fax machines... and i don't know if the provider supports it or not... turned off ECM and also enabled re-invite with no success.

Looks like we'll just keep using RingCentral.com

 

[hairlessupportmonkey]

also - make sure the sip trunk isnt using g729

 

[hairlessupportmonkey]

also, not all providers offer proper FAX support. the interconnects between an IP exchange into a PSTN network can cause faxes to error.

Its only recently BTs 21cn network started supporting faxing over it!

 

[jmlee]

hairlesssupportmonkey, we are using g729 but yesterday while working with the vendor we changed to 711 but still no success...

 

[Bas1234]

on the fax itself set the tx/rx speed to 9600 baud

___________________________________________
It works! Now if only I could remember what I did...

Dain Bramaged
___________________________________________

 

[mforrence]

@jmlee - you'll never get it to work on 729. 711 is your only option.
Mike

 

[tlpeter]

You need to use T.38 for faxing over sip.


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