Call Termination On Fxo Devices; Calls Termination By Pbx - AudioCodes Mediant 800 User Manual

CHAPTER 29 Analog Gateway
■ Hold / Transfer toward the Tel side: The ini file parameter LineTransferMode must be set to
0 (default). If the FXO receives a hook-flash from the IP side (using out-of-band or RFC 2833),
the device sends the hook-flash to the Tel side by performing one of the following:
● Performing a hook flash (i.e., on-hook and off-hook)
● Sending a hook-flash code (defined by the ini file parameter HookFlashCode)
The PBX may generate a dial tone that is sent to the IP, and the IP side may dial digits of a new
destination.
■ Blind Transfer to the Tel side: A blind transfer is one in which the transferring phone
connects the caller to a destination line before ringback begins. The ini file parameter
LineTransferMode must be set to 1.
The blind transfer call process is as follows:
● FXO receives a REFER request from the IP side
● FXO sends a hook-flash to the PBX, dials the digits (that are received in the Refer-To
header), and then drops the line (on-hook). Note that the time between flash to dial is
according to the WaitForDialTime parameter.
● PBX performs the transfer internally
■ Hold / Transfer toward the IP side: The FXO device doesn't initiate hold / transfer as a
response to input from the Tel side. If the FXO receives a REFER request (with or without
replaces), it generates a new INVITE according to the Refer-To header.

Call Termination on FXO Devices

This section describes the device's call termination capabilities for its FXO interfaces:
■ Calls terminated by a PBX (see
■ Calls terminated before call establishment (see
■ Ring detection timeout (see

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
unknown, define them in the CPT file. The tone produced by the PBX / CO must be recorded
and its frequencies analyzed. This method is slightly less reliable than the previous one.
Relevant parameters: [DisconnectOnBusyTone] and [DisconnectOnDialTone].
■ Special DTMF code: A digit pattern that when received from the Tel side, indicates to the
device to disconnect the call.
Relevant parameter: [TelDisconnectCode].
■ Interruption of RTP stream: Relevant parameters: [BrokenConnectionEventTimeout] and
[DisconnectOnBrokenConnection].
Mediant 800 Gateway & E-SBC | User's Manual
Call Termination by PBX)
Call Termination before Call
Ring Detection Timeout)
- 733 -
Establishment)