Alcatel Unleashed

Hi all,

I hope this is the right thread as the topics are multiple related.

Well, i am running an H.323 trunk to a third party gateway which works pretty good.
When using SIP trunking everything works fine (Fax over T.38 or G.711).
But when running the H.323 protocol T.38 only works for incoming calls due to some protocol interoperabilities and it seems that there is no chance using G.711 for facsimile over speech channel.

So i am really want to know if there is any noteworthy addresses (maybe some undocumented) which could help me out running facsimile transmission over the G.711 channel. I am pretty sure that it would work when i could disable any Fax (CNG tone) detection within the PBX.

Any ideas?

What kind of gateway?
On ABPS you will find some interworking reports regarding OXO and Audiocodes using both SIP and H.323 Maybe they can be helpful for you.

Hi,

I tried several Gateways like Siemens, Cisco, Avaya and also the XCAPI VoIP solution...

I've access to the application partner site, but i can't find any OXO/Audiocodes related docs.
Can i find the document within the "The Technical Knowledge Base"?
Is there any specific (TCxxx or TGxxx?

Thank You

Go to VoIP/VoIP Parameters/Fax tab, set UDP to 1 and Framing to 3, this should fix it.

By clicking on the area you are having issues with, then hit F1 on your keyboard, the OMC Help File will open at the same area to guide you.

From this page:

"General description
This screen is used to manage the parameters specific to the Fax function on IP.

Description of fields
UDP Redundancy
Description
In order to ensure the reliability of the UDP transmission, the packets are sent several times to ensure that the information reaches its destination; this mechanism is called "UDP Redundancy".

Value
Between 0 and 2 (default = 1).


Framing
Description
In order to reduce bandwidth use, the framing mechanism (RTP Packetization) allows the compression of packets of the same type of compression as Fax packets.

Value
Between 0 and 5 (default = 3)."

Cheers,

MTC

Hi,

Thank you for your reply, but this really does not fix the problem. I don’t think that this is a matter of UDP redundancy or frame settings.
I want to use facsimile transmission via g.711 in an H.323 environment.
Whenever the OxO gateway detects the fax CNG tone, from the origin or the destination, the OxO send out a
"H.245: openLogicalChannel (t38fax) closeLogicalChannelAck" to the H.323 trunk. So how can I change this habit?
There is no switch, as far as I know, for disabling T.38 completely.

When running SIP i can choose between T.38 or G.711 for FAX within the "Gateway Parameters". Maybe i can do the same for H.323 in some way.


Any comments would be appreciated.

-SAN

Hi San

You don't have the same fields with H323 as you have with SIP. If you have how to change your system for SIP you will have better results. I have an oxo with R7.10_052.007 logged with SIP sever, I send fax with G711 normally. I scheduled it with redundance and G711 at the gateway parameters and it works fine.

Best regards.