EMEA IP Office Technical Tip
045: Analogue Trunk Disconnect Clear Operation
*Release Date: 19 July 2004
The IP Office uses two methods to disconnect Analogue calls :-
1) Line Break Disconnect (also known as Reliable Disconnect)
Detection of a Line Break condition (defined as < 5mA loop current in the line) for a period greater than that set by the Disconnect Clear Timer.
2) Tone Disconnect
Detection of a continuous Busy, or NU Tone, for 6 seconds.
Currently the Line Break Disconnect is only available for USA, Canada and UK, all other countries use Tone Disconnect.
When the Analogue Trunk -> Disconnect Clear checkbox is Selected the IP Office will disconnect a call whenever it detects a Line Break condition on the Trunk for a time greater than that set in the Analogue Trunk -> Disconnect Clear Timer box ( + 120mS) -
i.e. the IP Office expects a Line Break Disconnect event on this Trunk and NOT a NU/Busy Tone Disconnect.
When the Analogue Trunk -> Disconnect Clear checkbox is Not Selected the IP Office will only disconnect a call on that Analogue Trunk when it detects a 6 second continuous NU/Busy Tone - i.e. it never tries to detect a Line Break Disconnect event.
For those countries that use Tone Disconnect to clear a call (i.e. all countries except USA, Canada and the UK) the IP Office sends special information on initial call setup/connect when an incoming call from an Analogue Trunk is routed to the Voicemail
Server/Auto Attendant. If this call results in any form of Voicemail Recording/Message the Voicemail Server/Auto Attendant uses the special call setup/connect information to delete the last six seconds of any Recording/Message that is left (otherwise the
Recording/Message would contain the 6 seconds of Busy/NU Tone that is required to detect the Disconnection).
When the Analogue Trunk -> Disconnect Clear checkbox is Selected on a Trunk that does NOT provide a Line Break Disconnect event the IP Office will still disconnect a call when it detects a 6 second continuous NU/Busy Tone - i.e. the IP Office will disconnect this Trunk whenever a Line Break Disconnect OR a NU/Busy Tone Disconnect event is detected.
The Analogue Trunk -> Disconnect Clear option is Selected by the Manager Application by default.
The Analogue Trunk -> Disconnect Clear option is Not Selected by the Configuration Wizard by default (i.e. Reliable Disconnect is Not Selected).