Sangoma Vega 3000G No Disconnect

The FXOs (telephones, for the most part) connected to my Sangoma Vega 3000G FXS ports are not disconnecting when calls are terminated. When calls are terminated on the far end I just hear a busy tone. Everything else works fine. When the FXOs terminate calls the far end (SIP) will disconnect. Any ideas?

Telephones are FXS’s! (Foreign Exchange Station)

Ordinary telephones do not have any out of band mechanism for signalling a disconnect from the FXO (Asterisk is the FXO here). It is not expected behaviour for phones to release the line at the end of an incoming call and that is a property of ordinary phones, not of the PABX.

There are way in which exchanges can signal disconnect to stations, but, in general only things fax machines and other exchanges (and maybe answering machines) will look for those. Asterisk can be configured to recognize some of those. I’m not sure whether it can be set to generate all of them.

On two wire lines, the exchange can temporarily remove battery voltage, or it can play busy tone.

Maybe I’m using the terminology improperly but FXS provides dial tone, not FXO. The Vega 3000G is FXS and the telephone is FXO. Asterisk just sees it as a SIP channel. I’m sure whatever needs to be done needs to be done on the Vega 3000G.

The Vega has FXS ports, which means ports intended to be connected to FXS’s. The phones are FXS’s.

The protocol for hanging up an ordinary, analogue phone is that the callee listens to the incoming audio and hears the caller saying “goodbye”, or possibly a busy tone, or even, for an outgoing line, possibly dial tone, and then hangs up the phone. The phone doesn’t detect that the remote end has ended the call. This has been true since long before VoIP.

In fact, what used to happen, on the PSTN, is if the callee didn’t hang up their phone at the end of a call, after a delay, the exchange would send a very loud, “howler”, tone as audio, to attract the subscriber’s attention, so that they did hang up the phone.

Sangoma don’t seem to want you to know about the real capabilities of the device, as I’m unable to find a detailed user guide for configuration on their site (and even third party sites don’t go beyond the external pinout), but the sales materials don’t mention any disconnect supervision capability, and, as I’ve already pointed out, ordinary analogue phones do not detect disconnect supervision signals.

Tell me about it… documentation is nonexistent. I was working with a phone that I believe is supposed to recognize the disconnect. I was hoping someone might know how make the Vega 3000G log the signals. If not I will find some hardware that can tell me if the signal is actually being generated. I had expected it was, as you said, the battery voltage being removed. I can’t verify if the gateway is actually doing this.

It may not be easy to find on Sangoma’s site but the top Google search result for “sangoma vega config file” is a 340-page manual.

p. 225 has disconnect supervision options for FXS.

The Vega Gateway Management module for FreePBX is a nice provisioner and allows you to edit the config from the GUI rather than at the Vega CLI.

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