Fixup command and VOIP

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May 9th, 2008
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hi all,

We recently implemented VOIP on one of our sites, the main callmanager is in the head office and all traffic goes through a PIX 515. The VOIP phone would get the correct IP address from DHCP but simply didnt work properly. After removing the fixup h232 command it started working fine, can someone pls explain exactly what fixup does and how removing it fixed the prob? Thanks in advance.

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hadbou Thu, 05/15/2008 - 05:46
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"Application Inspection" is also known as "Fixup".The fixup protocol h323 command provides support for H.323-compliant endpoints. PIX Firewall Version 5.3 through Version 6.2 supports H.323 Version 2. PIX Firewall Version 6.3 supports H.323 Version 3 and Version 4.

H.323 is a suite of protocols defined by the International Telecommunication Union (ITU) for multimedia conferences over LANs. H.323 supports VoIP gateways and VoIP gatekeepers. H.323 Version 2 adds the following functionality:

"Fast Connect or Fast Start Procedure for faster call setup

"H.245 tunneling for resource conservation, call synchronization, and reduced set up time


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