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FXS port staying off-hook when remote call hangsup

Alex Fassas

October 17, 2018 04:42

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I have a Yeastar TA800 FXS Gateway that is providing analog trunk CO appearances for our legacy Samsung iDCS100 PBX.  We have an installation of FreePBX version 14 on the same LAN with the gateway that connects to our SIP provider.  The FXS Gateway does "port register" for each of the ports with our FreePBX.

The FXS Gateway is working and allowing our legacy PBX to dial out and receive SIP calls via the FXS Gateway ports that are simulating the PSTN Loop Start CO lines.

The issue is when a SIP call that is external to the FXS Gateway hangsup and our Samsung PBX SVMI voicemail auto attendant is on the line.  The auto attendant does not recognize the call has ended and does not hangup.  The FXS port remains off-hook for 10 minutes.

When an external caller hangsup, the FXS port hears a fast busy signal, but does not actually do any sort of audible disconnect that I can discern. 

Yeastar support said the following, "For our TA device, currently we have two hangup signal to the end device connect to it. One is busy tone signal, and the other is polarity reverse. When the caller hangup, we'll off the end units either of that two signal and expect the end unit can detect it and hang up itself, otherwise the end unit will still keep alive and cause the port off hook. So please help us check what kind of hang up signal your legacy PBX accept and change to that hang up signal."  I have tried changing the TA800 port to "Polarity Reverse=YES" with no change in the hangup behavior.

I am disappointed that the FXS port does not disconnect first on external caller hangup, but rather waits for the device connected to the FXS port to go On-Hook.  I would appreciate some advice from some of the more experienced here to get my FXS port to go On-hook when someone hangs up on the voicemail auto attendant.

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8 comments

• 0
  
  Oscar Colka October 17, 2018 05:33

  Alex, is it possible to access to your side through teamviewer? This sounds abnormal. Maybe there is some issue releated to SIP, I would like to have a look if you trust me.

• 0
  
  Oscar Colka October 17, 2018 05:40

  http://www.yeastar.com/download/QuickSupport.rar

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  Vitaliy October 17, 2018 13:54

  Good day!  i have same problem

  3CX + Yeastar TA1600 - Freezes calls after transfer

  Configured:
  3CX server
  gateway Yeastar TA1600
  Secretary Yealink T27G phone
  
  Everything works fine, except for one moment.
  - The subscriber calls an external number, after greeting gets to the secretary
  - Requests to connect, the secretary translates with the consultation
  - The call translates, people communicate
  - But in active 3CX calls, the call between the secretary and
  internal subscriber. Even when the conversation ends, this call
  will remain hanging forever until you manually kick it on 3CX.
  At the same time, on the secretary’s panel the red light is on for this employee. If
  translate WITHOUT advice, then everything goes like clockwork. Such
  observed only in conjunction with Yeastar, connected a number of SPA122, everything is there
  runs smoothly as it should. Firmware on the gateway last, out of the box.
  
  What advise you to try? thanks in advance

• 1
  
  Larry Neblett October 17, 2018 14:36

  The disconnect is sent. As you stated, you hear a fast busy. This is used by some devices to indicate disconnect. Polarity reversal is as well. 

  However, there is another disconnect signal which is the absence of voltage for a period of time which is referred to as open loop disconnect. This is probably the more common disconnect signalling used, at least in North America. 

  When FreePBX sends a BYE, the result is the FXS port then sends the busy as a disconnect tone to the legacy PBX. The issue is whether or not you can find a compatible setting in the legacy PBX that will work with what's available in the TA. 

  Polarity/Battery reversal is not used much anymore and I can't think of when the last time I saw one, come to think of it (in the US). I suppose it possible that where you are located it may still be in use. 

  The TA, I suspect, is normally expected to be connected to a handset and the caller and callee would hangup and the other would too when each said goodbye or the one that stayed on would then hear the fast busy and then hang up. I see where it could be a problem for any auto-answer device such as a fax or answering machine. 

  However, the issue is that the legacy PBX must be able to match a disconnect type supported by the TA. If that is not possible, then a different make of gateway should be considered that supports open loop disconnect. There are a number that do.

   

   

• 0
  
  Jason Poth November 16, 2018 23:31

  I have the exact same issue connecting to an ESI phone system.  What is the fix?  I have a TA1600

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  Alex Fassas November 26, 2018 22:18

  Our issue was with a TA800 FXS Gateway.  I am going to paste my support responses here so that it may be helpful for others.  I am the OP.

  From Yeastar support:
  For our TA device, currently we have two hangup signal to the end device connect to it. One is busy tone signal, and the other is polarity reverse. When the caller hangup, we'll off the end units either of that two signal and expect the end unit can detect it and hang up itself, otherwise the end unit will still keep alive and cause the port off hook. So please help us check what kind of hang up signal your legacy PBX accept and change to that hang up signal.  

  Additionally from Yeastar support:
  Thank you so much for your replying. Is there any place we can setup on the Samsung PBX to accept either busy tone or polarity reverse as a hang up signal? Since unfortunately we're not supporting loop current disconnection for now. We're working on it, but honestly I don't have an ETA for that. 

  This is only an issue for inbound callers that are answered by the Analog PBX that the FXS Gateway is feeding calls to AND they get answered by the Automated Attendant.  The caller hangs up, the Auto Attendant does not and sends them to voicemail, until the voicemail times out max message.  We have shortened our max message time to help resolve. 

  In all fairness, Yeastar support did ask me to send a recording of the "fast busy" signal signaling that they were sending and do some testing.  We could not put anymore resources towards this issue and moved on.

   

• 1
  
  mustafa March 15, 2019 22:11

  happened to me once and the problem was tx/rx boosting ... i was setting it to 150% on s-series, so i decided to keep it 40% as it was the default value

• 0
  
  Darryl Panzer December 02, 2021 17:28

  This is a major issue for us.  I would think everyone is experiencing the same thing.  Please provide the loop current disconnect option to all models.  This is common in the US