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Problems with Analog Line Not Hanging Up


Author’s note:  This article supports our legacy products.  At Inventive Labs, after two decades of providing telephony tools, we never stop supporting those who rely on our products to run their businesses. For more information about these legacy products and where we are today, read  Ditch Dialogic & Convert to Voice Elements.


In the US, by default, a Dialogic analog board terminates a call when it detects a loop current drop.

If you have plugged your analog Dialogic board into a PBX or other device that is not directly connected to the PSTN line, then you may experience an issue where the system does not detect a hangup.

Most of the PBXs and switches today do not use loop current drop to notify the called or calling party of disconnection. Instead, they use a “disconnect tone”, which is usually the same as a busy tone. The disconnect tone is sent to a called party immediately after the calling party hangs up. In the other direction, there can be a delay of up to 30 seconds before the calling party receives the tone indicating that the called party has hung up.

By default, Dialogic cards detect disconnection as a result of loop current drop. This document provides instructions for changing that default so that disconnection is reported as a result of a disconnect tone.

Advanced Tone Feature

With this method, you use PBXpert or PBXpert/32 to capture the disconnect tone sent by the switch or PBX. (PBXpert generates a Tone Set File that contains tailored tone definitions for the switch connected to the Dialogic board at the time you execute the PBXpert utility.)

Once the tone set file is generated, you must define it to the Dialogic software. The tone set file is specified via the DCM. On the Misc tab for the board, set TSFFileSupport=Yes and DisconnectTone=Yes.

Then, on the Files tab, enter the name of the Tone Set File.

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