Gigaset N510 IP PRO Manual page 105

Defining local communication ports (listen ports) for VoIP
The settings for the communication ports are on the Web page:
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Settings Telephony
The following communication ports are used for VoIP telephony:
u
SIP port
The communication port via which the phone receives (SIP) signalling data. The
default standard port number is set to 5060 for SIP signalling.
u
RTP port
Two consecutive RTP ports (consecutive port numbers) are required for each VoIP con-
nection. Voice data is received via one port and control data via the other. The default
standard port number is set to 5004 for voice transmission.
This setting only has to be changed if the port numbers are already being used by other
subscribers in the LAN. You can then specify other fixed port numbers or port number
ranges for the SIP and RTP port.
If several VoIP phones are operated on the same router with NAT, it makes sense to use
randomly selected ports. The phones must then use different ports so that the router's
NAT is only able to forward incoming calls and voice data to one (the intended) phone.
Use the Web configurator to specify a port number range for the SIP and RTP port that the
ports are chosen from.
Configuring the phone via the Web configurator
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Advanced VoIP Settings
105