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Community Member

FXO and IP phone disconnect issue

Hello,

I'm working on the UC520 im my lab and what I'm trying to do is to fix the FXO disconnect problem, I know that it's a popular problem and I already checked the posts about it including the Cisco's document (Understanding FXO Disconnect problem). So here is my situation.

what I'm tryin to do is the make the IP phone hang up by itself when the other party end the call and the disconnect tone heared, (For Example: if you were talking on the speaker then no need to press the button to end the call, the speacker will be closed by it self. and the same if you were using the softphone).

here are some scenarios with my cuurect configuration:

let's say that the person who is calling from his mobile is person (A), and the one on his desk with the Cisco IP phone is Person (B)

  • When person (A) call and dial Person(B)'s Ext and then hang up (before person (B) pick up his phone), the ip phone does notkeep ringing and it hangs up as well. :)
  • When person (A) call and dial Person(B)'s Ext and person (B) pick up his phone then they talk for a while after that person (A) hang up his mobile , the ip phone automatically give a busy tone and hang up (the FXO port as well).:)
  • WhenPerson (B) call Person (A) on his mobile and then they talk for a while , after that Person (A) hang up his mobile, and let's say that Person (B) forgot to press the speaker button or he was using a softphone and he just took the headsets of. In this case the IP phone does not hang up and the FXO will still busy until the IP phone is hanged up. and this is a problem because in some cases especially with the softphones the person forget to click on the peacker button. :(

So, we have no problem when the IP phone hangs up the FXO disconnects. And we have no problem when the call comes from outside and then hangs up the FXO disconnects as well.

the only problem is happening when the call is made by the ip phone and then the other party hang up, in this case the FXO will stick off hook until the IP phone hang up.

So I know this was a LONG description but I hope that I made it cleare.

Any body has any Suggestions ?

9 REPLIES
Cisco Employee

Re: FXO and IP phone disconnect issue

There really shouldn't be any dependancy on the direction of the call with regards to disconnect supervision.  A couple of questions:

1. In your testing, is person A always the same mobile phone?

2. Do the inbound and outbound calls both use the same FXO line?

3. What mechanism are you using for diconnect supervision?  Your message seems to suggest tone detection, but I just want to be certain.

4. In your testing, when you talk about person A's mobile phone, is it *really* a mobile phone, or are you using another PSTN line for test purposes?

Cheers,

Dave.

Community Member

Re: FXO and IP phone disconnect issue

Thanks for your response, As I checked and as you said there shouldn't be any dependancy on the direction of the call with regards to disconnect supervision, but this is what's happening and confusing me.

1. In your testing, is person A always the same mobile phone?

  YES my mobile phone

2. Do the inbound and outbound calls both use the same FXO line?

   YES the Same one

3. What mechanism are you using for diconnect supervision?  Your message seems to suggest tone detection, but I just want to be certain.

I tried to use the tone detection and I got the signal using the Wireshark and cooledit softwars , but when I configured that frequencies it did not work, right now I'm using the ( supervisory disconnect dualtone mid-call) command. and here is the configuration for the FXO port:

voice-port 0/1/0
trunk-group ALL_FXO 64
supervisory disconnect dualtone mid-call
supervisory answer dualtone
no battery-reversal
cptone BR
timeouts call-disconnect 1
timeouts wait-release 1
timing hookflash-out 500
connection plar 200
description Configured by CCA CO Line - 0/1/0-CO0
caller-id alerting dsp-pre-allocate

4. In your testing, when you talk about person A's mobile phone, is it *really* a mobile phone, or are you using another PSTN line for test purposes?

NO it is a mobile phone.

Cisco Employee

Re: FXO and IP phone disconnect issue

Try removing the supervisory answer configuration.  Unless the exchange is actually sending tones to indicate that the outgoing call was answered, it seems likely that the UC500 is interpreting the disconnect tone as an indication that the call has been answered.

Cheers,

Dave.

Community Member

Re: FXO and IP phone disconnect issue

I tried that and I got the same results , but I noticed that the busy tone that I got when the mobile phone ends the call is not the same in the two situations. That means that when I make a call from the mobile to the IP phone and after speaking for a while the mobile end the call I got a different tone than if the call was made from the IP phone to the mobile and the mobile ends the call, the UC520 is able to get the first signal but not able to detect the second one.

So we have two different busy (Disconnect) tones, how can I configure that?  what's your suggestion ?

Cisco Employee

Re: FXO and IP phone disconnect issue

Hmmm.  How different are the two sets of disconnect tones in terms of frequency and cadence?  Are they wildy different or just slightly different?  We may be able to come up with a custom tone detection configuration that encompasses both tones, but if they are significantly different and we have to make the tolerances too wide, then the risk is that we may get spurious disconnects that result from other tones or noise on the line.

Cheers,

Dave.

Community Member

Re: FXO and IP phone disconnect issue

Hi Dave, thnak you for helping ...

here are the two sets of tones in terms of freq and cadence:

The First Disconnect Tone (The one which the UC520 is able to capture):

Freq : 421.8 Hz

Cadnece:              

  • ON  : 0:00.168
  • OFF: 0:00.250
  • ON  : 0:00.248
  • OFF : 0:00.251
  • ON  : 0:00.250
  • OFF : 0:00.251
  • ON  : 0:00.248

The Second Disconnect Tone (The which makes the FXO port stick off hook):

Freq : 421.8 Hz

Cadnece:              

  • ON  : 0:00.380
  • OFF: 0:00.500
  • ON  : 0:00.499
  • OFF : 0:00.497
  • ON  : 0:00.503
  • OFF : 0:00.501
  • ON  : 0:00.499

So what do you think ?

Cisco Employee

Re: FXO and IP phone disconnect issue

Sorry for the delay in responding to this.  Been a busy week. :(

Ok, given what you have captured above, one approach we can try is to set really sloppy tolerances on the cadence detection on the ports.  So try something like the following (which you will need to use the CLI to apply):

voice class custom-cptone MyDisconnectTone

dualtone disconnect
  frequency 422
  cadence 375 375
!

voice class dualtone-detect-params 1
cadence-variation 15

!

voice-port 0/1/0

supervisory disconnect dualtone mid-call
supervisory custom-cptone MyDisconnectTone
supervisory dualtone-detect-params 1
cptone xx  <--insert the appropriate country code for your location

!

This should result in the UC500 detecting as a disconnect any 422Hz repeating tone with a cadence of between 225ms and 525ms for the on/off times.  This should catch both scenarios you are hitting.

Let me know how you go.

Cheers,

Dave.

Community Member

Re: FXO and IP phone disconnect issue

Hi, now using this configuration the FXO port never disconnects. I did not have the time to make more detailed tests but as a first results now the FXO port does not disconnect in any situation.

I'll make some more tests and get back to you but if you have any more suggestions please let me know.

Cisco Employee

Re: FXO and IP phone disconnect issue

Ok.  In that case, I think this is time to call the TAC if you haven't already done so.  This is going to take a bit of work to get the settings right and probably should be done by getting a TAC engineer to log on to the box and work the problem through to completion.

Cheers,

Dave.

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