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Chapter 4 Basic and Additional SIP Services
Additional SIP Services
4-8
Cisco IP Phone Models 7905G and 7912G Administrator Guide (SIP)
OL-4277-01
NAT/PAT
translation
To maintain Network Address Translation/Port
Address Translation (NAT/PAT) for a session, the
Cisco IP Phone can be configured to periodically send
a dummy UDP packet to a server (the phone does not
expect any response from the server).
To specify this configuration, use these parameters:
• NatTimer—Bits 0 to 11 are for specifying the
retransmission period.
• NatServer—Specifies the server to which the
dummy packet is sent.
See the “SIP Parameters”
section on page 8-9.
Network timing You can fine tune your network timing by making the
following settings:
• Use the TimeZone parameter to specify the
time-stamp for incoming calls (offset from
Greenwich Mean Time).
• Use the NTPIP parameter to specify the IP address
of the Network Time Protocol (NTP) server. NTP
is a protocol built on top of TCP that ensures
accurate local time-keeping with reference to radio
and atomic clocks located on the Internet.
• Use the AltNTPIP parameter to specify an
alternate NTP server IP address.
• Use the ConnectMode parameter to specify the
connection mode of the SIP protocol.
See the “Network
Parameters” section on
page 8-2 and the “Audio
Parameters” section on
page 8-24.
Table 4-2 Additional SIP Services (continued)
SIP Service Description Reference