Firewalls And Sip; Configure Sip Timer Values - Cisco WRP500 Administration Manual

Chapter 2 Configure Your System for ITSP Interoperability
R E V I E W D R A F T # 1 — C I S C O C O N F I D E N T I A L
View the syslog messages to determine whether your network uses symmetric NAT. Look for a warning
Step 7
header in the REGISTER messages, such as Warning: 399 spa "Full Cone NAT Detected."

Firewalls and SIP

To enable SIP requests and responses to be exchanged with the SIP proxy at the ITSP, you must ensure
that your firewall allows both SIP and RTP unimpeded access to the Internet.
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•

Configure SIP Timer Values

The default timer values should be adequate in most circumstances. However, you can adjust the SIP
timer values as needed to ensure interoperability with your ISTP. For example, if SIP requests are
returned with an "invalid certificate" message, you may need to enter a longer SIP T1 retry value.
For more information, see the
Make sure that the following ports are not blocked:
SIP ports—UDP port 5060 through 5063, which are used for the ITSP line interfaces
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RTP ports—16384 to 16482
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Also disable SPI (Stateful Packet Inspection) if this function exists on your firewall.
"SIP Timer Values (sec) section," on page 8 of Appendix
Firewalls and SIP
Cisco WRP500 Administration Guide
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