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DTMF In trace


jag
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We are having trouble with our fax, so we switched trace on and we get 1000's of these messages in the trace. At first we thought it was the M3 phone, so we stopped that and these message still appeared.

 

What do they mean?

 

 

[9] 2008/08/18 16:40:55: DTMF: Power: 0 0 0 0 0 0 0 0 0

[9] 2008/08/18 16:40:55: DTMF: Power: 0 0 0 2 0 2 0 0 0

[9] 2008/08/18 16:40:55: DTMF: Power: 0 0 0 2 0 0 0 0 0

[9] 2008/08/18 16:40:55: Last message repeated 2 times

[9] 2008/08/18 16:40:55: DTMF: Power: 0 0 0 0 0 0 0 1 1

[9] 2008/08/18 16:40:55: DTMF: Power: 0 0 0 0 0 0 1 0 0

[9] 2008/08/18 16:40:55: DTMF: Power: 0 0 0 0 0 0 0 0 0

[9] 2008/08/18 16:40:55: Last message repeated 3 times

[9] 2008/08/18 16:40:55: DTMF: Power: 2 0 0 0 2 2 0 1 1

[9] 2008/08/18 16:40:55: DTMF: Power: 0 0 0 0 2 0 0 0 0

[9] 2008/08/18 16:40:55: DTMF: Power: 2 0 0 2 0 0 0 1 0

[9] 2008/08/18 16:40:55: DTMF: Power: 0 0 0 0 0 0 0 0 1

[9] 2008/08/18 16:40:55: DTMF: Power: 0 0 2 0 0 0 0 0 0

[9] 2008/08/18 16:40:55: DTMF: Power: 0 0 0 0 0 0 0 0 0

[9] 2008/08/18 16:40:55: DTMF: Power: 0 0 2 0 0 2 0 0 0

[9] 2008/08/18 16:40:55: DTMF: Power: 0 0 0 0 0 0 0 0 1

[9] 2008/08/18 16:40:55: DTMF: Power: 0 0 0 0 0 0 1 1 0

[9] 2008/08/18 16:40:55: DTMF: Power: 0 0 0 0 0 0 1 0 1

[9] 2008/08/18 16:40:55: DTMF: Power: 2 0 0 0 0 0 0 1 0

[9] 2008/08/18 16:40:55: DTMF: Power: 0 0 0 0 0 0 1 0 0

[9] 2008/08/18 16:40:55: DTMF: Power: 0 2 0 0 0 0 0 0 0

[9] 2008/08/18 16:40:55: DTMF: Power: 2 0 0 0 0 0 1 0 0

[9] 2008/08/18 16:40:55: DTMF: Power: 0 2 0 2 0 0 0 0 1

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We are having trouble with our fax, so we switched trace on and we get 1000's of these messages in the trace. At first we thought it was the M3 phone, so we stopped that and these message still appeared.

 

What do they mean?

 

Here you can see how the DTMF detection works. The PBX looks at 9 frequencies (the one in the middle is the FAX detection tone). If anything is significantly standing out (2 is not significant), then that tone is treated as "present". A DTMF tone has one of the first four and one of the last four frequencies.

 

Needless to say, this kind of logging literally eats the CPU. So turn this only on if you want to debug something with inband DTMF.

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Here you can see how the DTMF detection works. The PBX looks at 9 frequencies (the one in the middle is the FAX detection tone). If anything is significantly standing out (2 is not significant), then that tone is treated as "present". A DTMF tone has one of the first four and one of the last four frequencies.

 

A few fax numbers, when dialed, will occasional play a recording, “please enter your destination number, terminate the number with a # sign”.

 

The recording is definitely coming from his pbx. I verified this as there were no active trunk calls while this was happening. It seems as though the call is being redirected to a calling card account, yet none exist.

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