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4. Disconnect Tone Configuration
This application note is going to describe the procedures of configuring the
disconnect tone on VoIP FXO gateway in order to release LINE ports of VoIP
FXO gateway after PSTN/PBX caller party is hung up.
4.1 What is Disconnect Tone
A caller make a telephone call to gateway from PSTN side, VoIP FXO
gateway will answer the call automatically. If the IP side of other VoIP devices
do not answer the call and the caller hang up the call, the PSTN/PBX will give
gateway a disconnect tone automatically. Or, VoIP FXO gateways are
installed on both sied and connect to local PSTN. If both parties are in talking
mode and one side hang up the call. the VoIP FXO gateway has to recognize
the disconnect tone from local PSTN and release the line port with the
pre-defined busy tone or reorder tone in VoIP FXO gateway tone table.
There are three parameters received from PSTN/PBX.
- High level frequency and Low level frequency
- Tone Cadence (ON/OFF intervals)
- Tone level
These parameters have to be properly configured in VoIP FXO gateway in
order to recognize disconnect tone correctly. Each different PSTN/PBX have
different parameters. So, VoIP FXO gateway has to configure tone table when
line port connect to different PSTN/PBX.
4.2 How to configure disconnect tone on VoIP FXO gateway
VoIP FXO gateway has a default setting of disconnect tone (Busy tone 1,
Busy tone 2, reorder tone 1 and reorder tone 2 ). If the disconnect tone was
recognized correctly, the line port from PSTN/PBX will be released in seconds.
IP-Network
PSTN or
PBX
VoIP
FXO
gateway
Other VoIP
devices
IP Side
PSTN side
Caller