fxo : incoming calls - when no pickup, caller hangs up - but ip phones keep ringing

[Dalbir-Singh Sangha]

Hi,

I have an FXO port on a UC520 configured to make cisco ip phones ring when a call comes in through the PSTN. 

However, if there is no pickup of these ringing phones and then the caller hangs up - the phones continue to ring which is of course not desirable.

Anyone come across this issue ?

here is the config for the fxo port :

voice-port 0/10

connection plar 500

Thanks

Dalbir

[Payal Bhaduri · Accepted solution]

Hi,

you can try any of the following methods od disconnect:

1.voice-port x/x/x
  supervisory disconnect dualtone {mid-call
  cptone  {GB}    <--- You can try different values
  timeouts wait-release 5
  timeouts call-disconnect 5

2.voice-port x/x/x
  supervisory disconnect anytone
  timeouts wait-release 5
  timeouts call-disconnect 5

Also make the following change in order to check if Telco may be doing
battery reversal
based disconnect.

3. voice-port x/x/x
  battery-reversal
  timeouts wait-release 5
  timeouts call-disconnect 5

The default disconnect used is power denial which is configured by:

4. voice-port x/x/x
  supervisory disconnect signal
  timeouts wait-release 5
  timeouts call-disconnect 5

If none of this disconnect methods work then I always recommend to try to
contact your Telco so that they are able to tell you if their switch
provides disconnect supervision and what kind of method they use.

Also instead of the connection plar, can you use the connection plar opx 500.

[Payal Bhaduri]

If you provide me with the debug vpm signal while making the test call, i can tell you whether you are receiving the disconnect from the telco.

[Dalbir-Singh Sangha]

Hi Payal Bhaduri,

Thanks for your help with this.

I just have a couple of questions that maybe you could help with.

I am based in the UK and so to get the correct frequency and Cadence values i used the site:

World PSTN tone database :

http://www.3amsystems.com/wireline/tone-search.htm

I put in the values "Disconnect" and "United Kingdom" and the following values were returned :

Country Tone Freq/Hz Cadence/s

United Kingdom Disconnect tone 400 3~10 on

so as per your instructions i put these values in under a voice class:

voice class custom-cptone testUKPSTN

dualtone disconnect

frequency 400

cadence 310

Inputting the 'frequecy' was straightforward but for the cadence value above confused me.

As you can see I set the value to 310 but even though this worked i don't think it is

correct. under the cisco commadn for cadence above i have the following ranges :

UC520(cfg-cp-dualtone)#frequency 400

UC520(cfg-cp-dualtone)#cadence ?

<50-10000> First On Cadence

continuous Configure continuous cadence

I looked all over the web but would you know of a way to convert (3~10 on) to a value suitable for the command above ?

[Payal Bhaduri]

Hi,

Basically you can have a cadence value between the range 3 to 10. But if you want the exact cptone, you will need to do a PCM capture, and the exact cptone can be decoded using the PCM capture

[dijohn]

Here's a knowledge forum post on how to get a custom cptone without a PCM Capture..

http://ciscoflair.blogspot.com/2009/05/cisco-fxo-disconnect-issue.html

Which TELCO is this?. BT?.

PS: Rate useful posts.

[Dalbir-Singh Sangha]

Yes , this is BT telco.

Even though the range is 3 to 10 according to the website above ( if that what  3 ~ 10 means) (wasn't sure what the tilda ~ meant).

I actually put 310 for the cadence value and it worked...it must have been a lucky guess in the correct range of working values!

This worked but for the command, but the starting input value minimum value for cadence is 50 !  so i could not put in a range 3 to 10.