Page 164 of 910 Features
553-3001-365 Standard 4.00 August 2005
To avoid loss of the IP connection, the NAT Mapping Keep Alive function
sends the Watchdog Reset message more frequently. Default values are
recommended. However, if it is necessary to increase the frequency of the
Reset Watchdog message, increase the NAT Mapping Keep Alive timer
value.
NAT Traversal can be configured to provision the length of time the audio
and signaling port mapping is refreshed. This configuration can be done in
Element Manager, on the Call Server in LD 117, or in OTM through a
window to the Call Server.
By default, all IP Phones behind a NAT device have the signaling and audio
path kept alive. The default value is 30 seconds. The value can be decreased
to 20 seconds or increased to 600 seconds.

Mute and Hold considerations

IP Line 4.5 must handle two special situations when interworking with NAT:
Mute and Hold.
Mute
Table 26 describes the Mute process.
Table 26
Mute process (Part 1 of 2)
Description
Problem
1When a user enables Mute, the LTPS sends a Mute Transmit (Tx) command to the
IP Phone. That command forces the IP Phone to generate silence in the transmit
direction.
2If the IP Phone is using an evocator that implements silence suppression, for
example G.729AB, the IP Phone sends one silence frame to the far end, and then
stops sending any further frames until Mute is cancelled.
3Data sent from the IP Phone stops.