NAT
SIP NAT traversal
Requirements:
• configured DNS server
• When the activated option is selected: Registrar is enabled for the telephone
Active
NAT traversal is performed by the telephone. The SIP request also contains an "rport" part in which the IP addresses used here (local, public) are transported.
Active with STUN
NAT traversal is performed by the telephone. To do this, you must also specify a STUN server.
Caution: Each time a port is opened on the NAT router, this creates a potential security risk. Implement appropriate security measures.Inactive
NAT traversal is not performed by the telephone. The router which connects the local area network with the Internet should be a properly functioning SIP-aware router which performs NAT traversal.
Further help under IdentitiesRTP NAT traversal
Requirement:
• configured DNS server
Active with STUN
NAT traversal is performed by the telephone. To do this, you must also specify a STUN server.
Caution: Each time a port is opened on the NAT router, this creates a potential security risk. Implement appropriate security measures.
Note: if there are problems with half-open (dropped) call connections, a STUN server should be used (Active with STUN).Inactive
NAT traversal is not performed by the telephone. The router which connects the local area network with the Internet should be a properly functioning SIP-aware router which performs NAT traversal.
Further help under IdentitiesSTUN server URL
Requirement:
• configured DNS server
Note: The STUN server is used if Active with STUN has been selected.
Further help under IdentitiesSTUN server port
1 … 65535
Note: If you encounter problems with half-open (dropped) call connections, enabling the RTP port might help.
Important: Every time port forwarding is performed, there is a security risk. For this reason, we recommend you use port forwarding as little as possible. Further help under IdentitiesTime lapse registration (min.)
1 … 60 minutes
The registration time is the number of minutes that must elapse before the telephone reregisters itself with the VoIP provider.
The value you enter here should be a compromise between a short timespan (which generates traffic with the provider) and a long re-registration period.
Further help under IdentitiesNAT Keep-Alive Interval (sec.)
After the time specified here has passed, NAT Keep-Alive packets are sent to the firewall to maintain the NAT mapping.
Note: Some providers lock accounts if the NAT Keep-Alive Interval is too short. As a rule, this is reported with error message 503 during SIP registration. If this problem occurs, we recommend you reduce the value (e.g. to 180). Further help under Identities