Mute calls being dropped after one minute

Discussion in '3CX Phone System - General' started by luisalonsoramos, May 16, 2011.

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  1. luisalonsoramos

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    Hello,

    My users have reported a few times this week that calls are been dropped at around 15 minutes. I haven't experienced it yet, but I haven't done much testing (mostly because I don't know how to reproduce the problem yet).

    I am using 3CX v9 installed on a physical Windows 2003 Server (inside a Gigabit LAN), with 4 softphones (3CXPhone) and 1 Cisco hard phone.

    Do you have any idea on possible causes of this problem? What should I check? What tests should I perform in order to get an idea of what could be wrong?

    I know the problem description is quite vague but I don't have much information yet.

    Thanks in advance!
     
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  2. willow

    willow Member

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    Re: Calls being dropped after 15 minutes

    sometimes a voip providor will let you select a limit on the amount of time a call can be active. this may be a start. Also you will need to post a log of the call so that we can see the sip messagings.
     
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  3. luisalonsoramos

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    Re: Calls being dropped after 15 minutes

    Thanks for your reply. I am using a Grandstream GX-4104 with three regular PSTN lines.

    How do I get the log of the call? Just the regular system log from 3CX Management website?

    Thanks!
     
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  4. luisalonsoramos

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    Re: Calls being dropped after 15 minutes

    After some tests, I think we have narrowed the problem. The call is dropped when there is no sound on it for about a minute (make a call, mute on both sides, and wait a minute).

    Any ideas?
     
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  5. leejor

    leejor Well-Known Member

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    Gateways usually have several methods to detect that a call (PSTN side) has ended, and various "threshholds" that need to be reached before disconnecting. If your phone lines have an option to open the phone line (sometimes called CPC /momentary disconnect ) when the PSTN side has hung up, then that is the most reliable and the only one you probably want to use.

    Your Gateway is probably set to use silence and drop the call after a set time, which you should be able to increase, if you want to continue to use that method.
     
  6. luisalonsoramos

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    Thanks. I found on the gateway the Silence Timeout setting (set to 60 seconds, #5 in the image attached.) I could up that, but it could mean that if the call is dropped, the line will stay open, right?

    How should I see if my lines/gateway support CPC?

    I am attaching the settings page for the FXO Termination in my gateway.

    Thanks!
     

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  7. leejor

    leejor Well-Known Member

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    The Current Disconnect option is the one to use if supported. You can test a couple of ways...if you have a meter, switch to 200 volt DC range an put it across the phone line after you have established a call, hang up the PSTN side..do you see a momentary (a second or so) drop in voltage (to zero)?

    The other, easier way, is to disable the silence time-out, place a call on a trunk, keep the VoIP extension off hook but have the PSTN caller/called party hang up. Does the trunk "drop" (go idle) after a few seconds?, If so then you should be able to rely on the Current Disconnect option to release the lines. If you later find that lines are not being released then you may have to add the silence detect with an increased time-out (maybe 5 minutes?), as a backup.
     
  8. netswork

    netswork Active Member

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    There are some tools you can get from here:

    http://www.sandman.com/

    One you may be interested in is the CPC tester. Like Leejor said there are many different ways the telco can signal disconnect. Usually a tone, voltage change or battery reversal.

    If your in the united states and not out in the middle of no where, CPC is generally used which is 0 volts DC for a certain time limit. Your gateway is setting that threshold to 100ms by default...which may be a little short. You can test this by making a call to an outside party, having the outside party hang up and then see if your system disconnects the call. I have seen situations with analog gateway and cell phone calls where the CPC does not get sent and the line hangs, that's where silence detection comes in. Silence detection should be your last ditch effort to get the call to disconnect. You could increase the value to something higher like 5 minutes. But know that if you have situations where your system does not recognize what ever signal comes from the CO it will tie up that line until the silence timeout. If this is your main line in a multi line hunt your next incoming call will ring busy...it will not go to the next line in the hunt. But I have seen the ring voltage on an incoming call disconnect a hung line.

    You can always call the telco and ask them what disconnect method they are using or ask them what phone switch type they use. If you find out what phone switch they are using you can google that switch and see what disconnect it uses.

    I would disable silence detection and see how that works.

    sandman has a CPC tester and a voltage meter could also come in handy for anyone working with POTS lines.
     
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  9. leejor

    leejor Well-Known Member

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    Don't forget that the only time you should have to make use of a disconnect feature (either CPC or silence) is if a call is left on hold or somehow "forgotten" while connected to 3CX, and the caller (PSTN line) hangs up.

    When you hang up the 3CX extension it should drop the call on that trunk, it doesn't matter, if at that point if the PSTN party has hung up or not.

    The CPC feature was popular with users of the old key systems, the ones where you pushed the red hold key, the line button popped up,and all phones had a winking light on one of the keys indicating a call was on hold. In that case if the caller hung up, the hold was released and the line was no longer tied up even if no one took the call off of hold. The same applied to analogue PBX's.
     
  10. netswork

    netswork Active Member

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    Hopefully 3cx handles that better than asterisk does. I have seen asterisk leave a phone line open even after the IP phone side disconnected. I had one system were it happened every single time if the PSTN side hung up before the IP side.
     
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  11. luisalonsoramos

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    Hi all,

    Thanks for your replies. I set the Silence Timeout to something like 10 hours and made these tests:

    * Called from my softphone to my cellphone, and hung up the cellphone. The line was still connected in 3CX Management console, until I hung up on the softphone.

    * Called from my cellphone to my trunk, and had no one answer. When I hung up the cellphone, the line went idle in a couple of seconds (again, in 3CX Management Console Port/Trunk Status)

    * Called from my cellphone to my trunk, and had someone answer, and then put the line on hold. I then hung up the cellphone and the line was still open, until I retook it on the extension and hung it.

    Is this the expected behavior? Or will I need the Silence Disconnect?

    I will perform the current measurement as soon as I get a multimeter.

    Thanks again!
     
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  12. luisalonsoramos

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    I found the multimeter and used it on one line. The voltage is still at around 54.7 V. I placed a call and it didn't change, and when I hung up it still didn't move.

    That means Current Disconnect is not supported? I am in Mexico with Telmex as my provider.
     
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  13. netswork

    netswork Active Member

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    The DC voltage drop is very fast and I doubt you would see it on the multimeter. The CPC tester from sandman will detect the CPC signal and tell you how many miliseconds it is.

    I have fought these problems in the past, not with 3cx, but with other systems, and I never came out on top. I would call your phone provider and open a trouble ticket. I would ask them to tell you what type of disconnect signalling they use. The problem is they are not required to send any disconnect at all, but they should be doing something. Then you have to set your gateway to "listen" for that signal.

    I did a little searching and from what I could find the standard disconnect in Mexico is a tone. Here is a copy and paste from another forum:

    "You need to set the disconnect tone to 425@-30,425@-30;1(.25/.25/1+2)

    This is provided your disconnect tone is the same as the standard Mexico busy tone (which it is most likely to be) of 425 hertz, 0.25 sec on, 0.25 sec off"


    I would try turning on number 2 on your FXO gateway to enable tone disconnect.
     
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  14. leejor

    leejor Well-Known Member

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    An analogue meter will show it, a digital one, not so much.
     
  15. luisalonsoramos

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    I have a digital meter, so that's why I didn't see it.

    I tried that setting but it still didn't work. I will call Telmex tomorrow and see what they tell me.

    I'll keep you guys posted. Thank you very much :)
     
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