SIP User's Manual 436 Document #: LTRT-12804
Mediant 800 MSBG
8.3.5.2.3 Call Termination on FXO Devices
This section describes the device's call termination capabilities for its FXO interfaces:
Calls terminated by a PBX (see ''Call Termination by PBX'' on page 436)
Call
s terminated before call establishment (see ''Call Termination before Call
Establishment'' on page 437)
Ring d
etection timeout (see ''Ring Detection Timeout'' on page 437)
8.3.5.2.3.1 Calls Termination by PBX
The FXO device supports various methods for identifying when a call has been terminated
by the PBX.
The PBX doesn't disconnect calls, but instead signals to the device that the call has been
disconnected using one of the following methods:
Detection of polarity reversal/current disconnect: The call is immediately
disconnected after polarity reversal or current disconnect is detected on the Tel side
(assuming the PBX/CO generates this signal). This is the recommended method.
Relevant parameters: EnableReversalPolarity, EnableCurrentDisconnect,
CurrentDisconnectDuration, CurrentDisconnectDefaultThreshold, and
TimeToSampleAnalogLineVoltage.
Detection of Reorder, Busy, Dial, and Special Information Tone (SIT) tones: The
call is immediately disconnected after a Reorder, Busy, Dial, or SIT tone is detected
on the Tel side (assuming the PBX / CO generates this tone). This method requires
the correct tone frequencies and cadence to be defined in the Call Progress Tones
file. If these frequencies are not known, define them in the CPT file (the tone produced
by the PBX / CO must be recorded and its frequencies analyzed -- refer to Adding a
Reorder Tone to the CPT File in the Reference Manual). This method is slightly less
reliable than the previous one. You can use the CPTWizard (described in the
Reference Manual) to analyze Call Progress Tones generated by any PBX or
telephone network.
Relevant parameters: DisconnectOnBusyTone and DisconnectOnDialTone.
Detection of silence: The call is disconnected after silence is detected on both call
directions for a specific (configurable) amount of time. The call isn’t disconnected
immediately; therefore, this method should only be used as a backup option.
Relevant parameters: EnableSilenceDisconnect and FarEndDisconnectSilencePeriod.
Special DTMF code: A digit pattern that when received from the Tel side, indicates to
the device to disconnect the call.
Relevant ini file parameter: TelDisconnectCode.
Interruption of RTP stream: Relevant parameters: BrokenConnectionEventTimeout
and DisconnectOnBrokenConnection.
Note: This method operates correctly only if silence suppression is not used.
Protocol-based termination of the call from the IP side
Note: The implemented disconnect method must be supported by the CO or PBX.
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