SPA-3102 Line Port terminated calls are hanging (stuck) issue

Pradeep Hapuarachchi · ‎03-10-2016

Hi Guys....

I have SPA3102 configured to SIP provider Callcentric.com. My SPA is with latest Firmware.

There is NO problem to make calls between SIP numbers (callcentric generated numbers). However I have configure the Line port of the SPA3102 is to terminate out the calls thru connected PSTN line. Almost all the settings of the SPA is as per recommended by the Callcentric provider and no complicated setting or any complex Dialplans what so ever.

Problem is whenever my friend uses this system to make Terminated calls thru SPA3102’s Line port connected PSTN line, sometimes when he end the call (after his intended discussion), line hangs. Basically it is NOT disconnecting the far end leg of the call between SPA3102’s Line port and other end (it could be a mobile call or maybe even a PSTN call). What I believe is SPA is NOT properly sending the ‘Disconnection Signal’ to the far end Mobile or PSTN call.

Only issue is at his place there is NO PC connected to get any trace logs (Wire shark or whatever). Would you recommend me some standard parameters in the SPA3102 to eliminate this Call hanging issue ?

Also noticed there is thread "SPA3102 does not detect disconnect tone when call was originated from PSTN!!!" but 6 years ago. However NO any conclusion in the this community unfortunately. I hope Dan or Howard Wittenberg would be able to take this up :)

Dan Lukes · ‎03-10-2016

So the call in question has arrived thru PSTN to SPA3102 and has been routed via local line to an automatic end device ? Or we are speaking other call direction of ?

Pradeep Hapuarachchi · ‎03-11-2016

hi Dan, thanks

Actually it is other-way around. Call comes from "VOIP to PSTN gateway" path. My end it is a VOIP /SIP call generates using another PAP2T device and trying to go as Outbound call thru PSTN port.

Dan Lukes · ‎03-11-2016

Well, it seems I still don't understand the topology. Is it this one ?

Analog Phone 1 <-> PAP2T <-> SIP <-> SPA3102 -> PSTN ... ... -> Phone 2

Calling phone is Analog 1.

Analog 1 phone unseize line to PAP2T, call should be terminated. But SPA3102 still holds the PSTN seized.

Is it correct description ?

Pradeep Hapuarachchi · ‎03-11-2016

Hope the attached image will explain faster..

Dan Lukes · ‎03-12-2016

Well, the so called 'disconnect signal' is very simple - the line loop is disconnected. It's almost impossible to send such signal incorrectly.

Thus we should check SPA3102 state. It's UI should be reachable if you can configure the ADSL to forward an incoming connection to SPA3102.

Also, it would be nice to have syslog&debug. It's not necessary to catch them locally - they can be received by any server. Even I can run receiving syslog server if no better server can be arranged.

We need identify who's guilty. PAP2T may not receive disconnection from calling phone. SPA3102 may not receive bye from PAP2T. And, of course, SPA3102 may not disconnect PSTN line despite asked to do it. Syslog messages may help us to analyze.

Pradeep Hapuarachchi · ‎03-12-2016

understood. Let me see the possibilities of getting the Syslog over to remote location. But the only concern is this is NOT happening 100% all the time. It happens only adhoc basis. Never be able to predict at what time with which call.

Since the ISP provides dynamic IPs to clients I am not sure how to grab the syslog from a device sitting behind the ADSL router. I am not sure whether I need to BUY a DynDNS account and setup and do that ... Any-other straight forward ways of grabbing ths SysLogs ?

Dan Lukes · ‎03-12-2016

 this is NOT happening 100% all the time

Well, it take time to wait. We just should capture state of the devices on the path once it will happen ...

The syslog client behind NAT is client - you need not know the client address on the server (unless you wish to limit access by firewall). DynDNS is either unnecesarry or it doesn't help.

Well, I has started a syslogd server on 78.128.192.2. Such server will accept messages from you. You may use it if you wish (even fr PAP2T at the same time). Of course, syslog messages are send using unreliable UDP protocol, so some messages may be lost in transit - so a server more local to client will be better. But you may consider it last resort choice.

Lets me know even if you consider not to use it so I can stop it.

Don't forget to read status pages on both PAP2T as well as SPA3102 once line once line cease to disconnect..

Howard Wittenberg · ‎03-13-2016

Pradeep,

When the voip side of the call discconnects, ths SPA3102 PSTN Tab logic will receive a sip BYE signal. I don't understand all the logical reasons as to why that does not always cause the SPA3102 FXO port to go on hook but it does not always do that after the call is connected. I am sure there are valid reason that the SPA3102 waits for a disconnect signal from connected PSTN end of the call.

Your PSTN company should be signalling that their client has hung up (discontinued) the call. Depending on the central office servicing the accout, this is signal in the form of a "CPC Signal" which is the dropping of voltage on the line for a period of time, or a "Disconnect Tone" which is a specified tone. Disconnect Tones vary depending on the country and the SPA3102 has a field available to specify the tone used in your country. It could also be in the form of a polarity reversal.

The SPA3102 has provided a setting that you can enable in the event your PSTN company is failing to issue a disconnect signal that the SPA3102 can detect. The setting is to disconnect the line after a predetermined period of silence. It is called Long Silence Disconnect. This setting is on the PSTN Line Tab. I would enable this setting.

Dan Lukes · ‎03-14-2016

I'm unsure, but didn't you missed the direction ?

In our particular case, the call is disconnected from callers side - e.g. the SPA3102 (the caller on the PSTN line) is initiating the hang. Thus no signal will arrive from PSTN side (as PSTN don't know the SPA3102s intention to hang).

Side note - on (somewhat ancient) stepping rotary based switches the callee is unable to disconnect call at all. If callee has placed handset to the cradle, nothing has happened. It has been possible to pick up the handset later - and the call has been still here. Only the caller has been eligible to initiate disconnection.

Thus we should not care what kind of CPC signal the PSTN is using.

Side note - the CPC is the Calling party control signal. It has been created to signal disconnection to callee. I'm not familiar with SPA3102 enough, but SPA122 doesn't detect CPC if they are caller, not callee. See also this brief article.

in the event your PSTN company is failing to issue a disconnect signal

In our case the PSTN will not generate disconnect signal as PSTN is not aware we wish to disconnect - we (e.g. SPA3102) need to claim our intentions to it.

Pradeep Hapuarachchi · ‎03-14-2016

Hi Howard, Thanks for the comments. I am not sure whether you seen my PDF diagram. May be worth checking it to understand exactly what I am trying to say. Do you need me to upload same ??

This similar setup I have few other places in Sri Lanka and NO call hanging issues like this. That is the strange thing. I even changed the SPA3102 to another NEW unit. However still ad-hoc behavior remains.

Also as you say I enabled the "Long Silence Disconnect" on the SPA3102, but the bad thing is, this causing even to disconnect the active calls also frequently. May be its detecting some 'blank spaces' since the 2 locations are far apart geographically. I even tested different values (seconds), but behavior was same. irrespective to the number of seconds I enter to the parameter, its still keep on disconnecting the active calls.

Pradeep Hapuarachchi · ‎03-14-2016

Hi Dan, Let me quickly reply. Thanks for providing a SysLog Server. I assume I need to put the IP 78.128.192.2 in the respective Tabs/places of the Call generation PAP2T as well as call termination end of SPA3102 correct ?

However I need few more days to do this as I said destination locations has NO PCs and I need to send someone with a laptop and do the IP setup. Please bear with me. As soon as I done I will let you know. In case if this SysLog sever is running 24x7 irrespective to me, please let it be, if NOT I will ask once my setup is done. On top of that is there any other things I need be aware of. ??

I have NOT read the comments today yet. Let me digest it .. :)

Dan Lukes · ‎03-14-2016

Yes, you can use 78.128.192.2 as the both syslog and debug server. The server is running 24x7.

Note I have no personal experience with SPA3102, so I wish Howard will help us with further analysis.

I need to send someone with a laptop

Try to configure remote ADSL router to forward incoming connections to SPA3102. It will allow you to reconfigure it with no laptop/personal presence required anymore.

Pradeep Hapuarachchi · ‎03-14-2016

Very delighted to hear this. However my challenge assume to be, even if I configure ADSL router to forward incoming connections to SPA3102, since the local ISP provides only Dynamic IPs to ADSL hence I will NOT know how to reach that device. Always my method was to user a laptop with teamviewer. When those days DysnDNS was free the above Task was easy for me by port forwarding.

If it is not a very big problem would you briefly comment this portion as well please ,....

Dan Lukes · ‎03-14-2016

You may use DynDNS. Or you may point Profile_Rule to an WWW server. It will not be used to serve configuration, but you will see from which IP the request has arrived. For the same purpose you may configure a fake SIP account or so - you need to catch those requests and see from where they are arriving.