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analog lines not getting disconnected

fadhumohammed
Level 1
Level 1

after a call is made from IPphone to mobile(for eg), even after disconnecting the call from IPphone its not getting disconnected on mobile...

inshort the fxo port is still active..the voice port remains off-hook..so gotta manually shut and open voice port from CLI everytime....

tried changing the cptone configuration(tried all the cisco provided configs(erricsson,alcatel etc))

regards

fadhu mohammed

1 Accepted Solution

Accepted Solutions

pcameron
Cisco Employee
Cisco Employee

As you have realised, this is the well known problem of supervisory disconnect, where the telco expects users to disconnect the call. They signal the end of the call by playing a disconnect tone to the party that is still off hook.

We can detect this tone and drop the call from the voice port if we know the frequency and cadence of the tones.

Here is a procedure you can use to determine these values (from an earlier posting of mine on Netpro)

Setting the cptone to KR will use the default settings for Korea, but we find that in many countries they do not use consistent tones across the entire nation, so even through cptone KR might work in one location, it may fail in another site. The best thing to do here is to get an ethereal/wireshark log of a call that is disconnected.

If you use G711 as the codec, we can easily save the audio payload out of ethereal as an AU file and can analyse the frequencies and the cadence (duration) of the tone. You should be able to plug a PC into the phone's PC port and capture the voice traffic.

All you need to do is to make a test call to the phone, then hang up from the PSTN side and listen for the disconnect tones to be played from the PSTN. Once you hear them, start wireshark and record the packet stream. We only need about 10 seconds or so.

We do this all the time to create custom tones for supervisory disconnect.

Here is an example -

!

voice class custom-cptone Korea_customtone

dualtone disconnect

frequency 480 620

cadence 300 200

!

We set up a custom disconnect class called 'Korea_customtone'. This will look for two tones of 480 and 620 hz, with a repeating on time of 300msec and an off time of 200msec

!

voice-port 0/2/1

supervisory disconnect dualtone mid-call

supervisory custom-cptone Korea_customtone

timeeouts call-disconnect 3

timeouts wait-release 3

!

To analyse the audio, you save the payload from wireshark as an AU file. (G711ulaw, 64Kbps, 8 bit, 8khz)

Search on the internet for an audio application called 'cooledit96'(which is now Adobe Audition)

Load the audio file into cooledit application.

Play back the audio to identify the disconnect tones

Use the cursors to highlight the start of the tone period, and then measure the on time duration. Do the same for the off time. This gives the cadence of the tones.

Move the cursor over the tone , then select Analyse-->Frequency Analysis

This will open a new window that shows a frequency domain view, and the two component tones are shown a individual peaks. Move the cursor over each tone peak and carefully read the displayed frequency (round it to the closest 5hz)

These values - cadence and frequencies are then used in the custom tone class.

View solution in original post

28 Replies 28

paolo bevilacqua
Hall of Fame
Hall of Fame

Hi, which exact IOS is running on the router ?

In this case, you should configure your own "voice class custom-cptone" (with the appropriate disconnect frequency and cadence) and then apply it for the voice ports.

How do we find out the frequency and cadence? We can use some recording tool to record the disconnect tone that we hear on the phone when the PSTN phone hangs up; take the frequency of the highest-amplitude point.

Hope this will help you as it has helped me a lot!

hoanghiep

yes....this is exactly wat i wanna know...how do we record the cptone...wats the name of the tool...pls help...

thanks a looooot anywyas...

and this is the ios tat iam using...

c2800nm-adventerprisek9-mz.124-15.T1.bin

I'm using Cool Edit Pro ver2.1.

thanks aloooot....can ya also gimme few tips on how to carry out the rocordings???? how to get the frequency and stuff....

Dear Sir

I have the same problem wity many customer can you help me how can use this sofrtware to know frequency and cadence

Thanks, Regards

Mohamed Maher

You can download cooledit96 here -

http://www.threechords.com/hammerhead/cool_edit_96.shtml

Use wireshark to capture the RTP, and save the payload in .AU format.

Load the audio file into cooledit and use the cursors to determine the on times and off times of the tones.

Select the Analyse option to do a frequency analysis. From the new window, you can move the cursor over the frequency peaks to determine the component tones. Round the frequency to the nearest 5hz.

use these values to create a custom disconnect tone class -

!

voice class custom-cptone test

dualtone disconnect

frequency 450

cadence 200 200

!

apply the custom class to the voice port

voice-port 0/0/0

supervisory disconnect dualtone midcall

supervisory custom-cptone test

And hope it works :-)

pcameron
Cisco Employee
Cisco Employee

As you have realised, this is the well known problem of supervisory disconnect, where the telco expects users to disconnect the call. They signal the end of the call by playing a disconnect tone to the party that is still off hook.

We can detect this tone and drop the call from the voice port if we know the frequency and cadence of the tones.

Here is a procedure you can use to determine these values (from an earlier posting of mine on Netpro)

Setting the cptone to KR will use the default settings for Korea, but we find that in many countries they do not use consistent tones across the entire nation, so even through cptone KR might work in one location, it may fail in another site. The best thing to do here is to get an ethereal/wireshark log of a call that is disconnected.

If you use G711 as the codec, we can easily save the audio payload out of ethereal as an AU file and can analyse the frequencies and the cadence (duration) of the tone. You should be able to plug a PC into the phone's PC port and capture the voice traffic.

All you need to do is to make a test call to the phone, then hang up from the PSTN side and listen for the disconnect tones to be played from the PSTN. Once you hear them, start wireshark and record the packet stream. We only need about 10 seconds or so.

We do this all the time to create custom tones for supervisory disconnect.

Here is an example -

!

voice class custom-cptone Korea_customtone

dualtone disconnect

frequency 480 620

cadence 300 200

!

We set up a custom disconnect class called 'Korea_customtone'. This will look for two tones of 480 and 620 hz, with a repeating on time of 300msec and an off time of 200msec

!

voice-port 0/2/1

supervisory disconnect dualtone mid-call

supervisory custom-cptone Korea_customtone

timeeouts call-disconnect 3

timeouts wait-release 3

!

To analyse the audio, you save the payload from wireshark as an AU file. (G711ulaw, 64Kbps, 8 bit, 8khz)

Search on the internet for an audio application called 'cooledit96'(which is now Adobe Audition)

Load the audio file into cooledit application.

Play back the audio to identify the disconnect tones

Use the cursors to highlight the start of the tone period, and then measure the on time duration. Do the same for the off time. This gives the cadence of the tones.

Move the cursor over the tone , then select Analyse-->Frequency Analysis

This will open a new window that shows a frequency domain view, and the two component tones are shown a individual peaks. Move the cursor over each tone peak and carefully read the displayed frequency (round it to the closest 5hz)

These values - cadence and frequencies are then used in the custom tone class.

i'll try this way and let ya know the response...thanks

hello,

iam able to save the payload as AU file but the playback is very wierd and so is the frequncy analyzed..

can ya help me with tat???(on how to properly save the payload as AU file so tat i can get a proper playback??)

Hi,

I am facing the same issue, ( Iam getting a wierd output)Could you please tell how you save the AU file out of wareshark & how did you find out the frequency ?

My Scenario is

Ana.Ph<->PBX<->FXO<-->FXO<-->PBX<-->Ana.Ph.

If I make calls from one ph to another the fxo port is not getting disconnected after I hangs up the phone.

Manoj.

Paul,

I've not suggested the supervisory disconnect issue, and asked instead for exact IOS, because the call goes to an IP phone, and there is a positive hang-up by said IP phone at the end of the call.

This should cause the FXO port to release in any and all cases.

As you know FXO - FXS (as an IP phone is, logically), should not cause the issue, that instead happens when using AA, CUE, etc.

hey...

i tried it out and its workin now..thanks...thanks alooot

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