Supervisory Disconnect

[griffinme]

We are tying a small Cisco phone router to our NEC 2400 to replace buried cables that have been trashed. There are only a few phones on it in a secondary building on our campus. It works great except for the disconnect detection. When someone hangs up the system doesn't realize it and it goes to voice mail and all the person gets is a message with the disconnect tones. Does anyone know what the tones are that are sent out over the analog lines?

The system is in the US if that matters. I heard that the tones vary from country to country and from PBX to PBX.

 

[OzzieGeorge]

We would need to know a lot more about the scenario to be able to offer any help (assuming we can)! How is the Cisco connected to the 2400? Why are you expecting the 2400 to detect tones? or the cisco for that matter, a cleardown should happen as a matter of course.

 

[griffinme]

The Cisco router is a 1760 with two FXO cards. Four analog lines from the NEC PBX go to the router's FXO cards (two per card). The problem is not with the NEC but with how the Cisco is detecting on hook on the analog lines. The Cisco has the capability to detect a multi-tone as the end of the call but it doesn't work well unless you specify what the tones are.

From the Cisco website

http://www.cisco.com/en/US/docs/ios...ucts_Command_Reference_Chapter.html#wp1106336

"Use this command first to create the voice class. Then use the supervisory disconnect dualtone voice-class command to assign the voice class to a voice port.

A voice class can define any number of tones to be detected. You need to define a matching tone for each supervisory disconnect tone expected from a PBX or from the public switched telephone network (PSTN).
Examples

The following example configures voice class dualtone 70, which defines one tone with two frequency components, and does not configure a cadence list:

voice class dualtone 100

freq-pair 1 350 440

freq-max-deviation 10

freq-max-power 6

freq-min-power 25

freq-power-twist 15

freq-max-delay 16

cadence-min-on-time 50

cadence-max-off-time 400

cadence-variation 8

 

[OzzieGeorge]

Have you put a Buttinski across the line to see if you get any tones at all? I don't have access to a 2400 at the moment to check myself.