59
SIP Operation Manual
PSTN Ring OFF Length: It is used to detect if the PSTN remoter party is on-hook through
the ring length from PSTN by FXO port. If the ring length form PSTN is larger than this
setting, it is going on-hook by FXO port, and it makes FXO not answering the call.
FXS Chip Option 1: It is to avoid mis-detecting the loop state of a subscriber line or PBX
user loop by FXS interface. In some places, the voltage of off-hook makes it mis-detect
the idle state and the active state by FXS interface. Untick this variable if it mis-detects
the state by FXS interface in your place.
Codec Settings
Preferred Codec Type: Since different voice codec have different compression ratios, the
sound quality and occupied bandwidths are also different. It is recommended to use the
default provided (G.723.1) because it occupies less bandwidth and will provide better
sound quality.
Jitter Buffer: Adjust the jitter to receive a packet. If the jitter range is too wide, it will delay
voice transmission.
Silence Detection / Suppression: If one side of a connection is not speaking, the gateway
will stop sending voice data (package) to decrease bandwidth usage.
Echo Cancellation: Prevents poor telecommunication quality caused by echo
interference.
Codec: Choose the codec that you needs.
Packet Interval: Defines how long the gateway sends a RTP packet (voice packet) to the
remote end. The larger the value, the more voice delay.
Approximate Bandwidth Required: The bandwidth required varies with codec format and
packet time.
