Configure a Phone 97SIPxNano IP-PBX Getting Started Guide B • Firewalls and NATConfigure a PhoneOnce you have identified the external IP address and opened ports for the incoming VoIP traffic on yourpacket-based firewall, you configure the phone to use those same values. Use the phone’s browser-based inter-face to:• Identify the external IP address• Set the SIP port• Set the RTP/RTCP portsIdentifying the external IP addressPHONESET_EXTERNAL_IP_ADDRESSThe “Host address outside NAT firewall” device setting applies to all phones that make calls through a firewall.You supply an IP address or host name that is outside of the firewall as the value for this parameter.For example:209.251.66.16In a configuration file, this address appears as follows:PHONESET_EXTERNAL_IP_ADDRESS: 209.251.66.16The phone includes this IP address or host name in the SIP messages it sends to other SIP user agents to indi-cate that this is the address to which SIP, RTP, and RTCP packets should be sent.Setting the SIP portTo define the SIP port, you set two different device settings to the same value. Both the port for inbound SIPTCP messages and the port for inbound SIP UDP messages must be set to the phone's assigned SIP port num-ber.Setting the RTP/RTCP portsThe Starting port for RTP/RTCP packets device setting identifies the first in a pair of consecutively num-bered ports. RTP and RTCP use these ports to receive audio media and control information for each concur-rent connection. The starting port defaults to 8766. You do not need to explicitly set the next port.Note You can open several pairs of consecutively numbered ports on your firewallto support more than one concurrent call. If so, you still define only thestarting RTP/RTCP port on the phone with this parameter.
