Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
Community Member

deb fax relay t30 level-2

Is there something to interpreter the result of deb fax relay t30 level-2 ?

I have some problem related to T38 fax Protocol, but I'm not able to understand where is the problem (Cisco 2811 & 2611 AS5400 PGW HSI GK enviroment)

Cisco Employee

Re: deb fax relay t30 level-2

Not really. This debug will show both t.30 and t.38 debugs.

It will show the actual t.30 or t.38 fax messages such as CNG,LCS and EOM.

You can find the state diagram for t.30 on the ITU site:

section 4.2 figure 9.

For PGW/HSI, you can either do GW controlled fax or call-agent controlled fax. If you have all cisco GWs, gw-controlled fax is simpler to configure.

If you are doing call-agent controlled faxing, make sure fax is enabled on the PGW/HSI:

(t.38 is desirable rather that t.30)

A good overall doc:

Hope this helps

Community Member

Re: deb fax relay t30 level-2

I have tried to decode a trace as suggest, but I have a lot of difficulties. Could you please help me decoding the below trace?

I'll try to use your example for the new one.

see atthaced trace.


Cisco Employee

Re: deb fax relay t30 level-2

No way to do this with the level 2 debugs, use debug fax relay t30 all instead to get an idea of what is happening. The other option is to use a fax probe such as those from genoa.

Hope this helps.

CreatePlease to create content