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COMmander 6000/R/RX - Firmware V7.0D - Advanced Information V19 04/2018
Settings – Public switched tel. networks
Voice over IP (VoIP)
Interval for NAT Keep-Alive enabled
After the time specified here has passed, NAT Keep-Alive packets are
sent to the Firewall to maintain the NAT mapping.
Note:
Some VoIP providers block accounts if the
Interval for NAT
Keep-Alive
is too short. As a rule, this is reported with error message
503 during SIP registration. If you encounter this problem, we
recommend you set a higher value (e.g. 180).
Caution:
Each time a port is opened on the NAT router, this
creates a potential source of danger.
•
It is essential you put additional protective measures in
place.