Hi Bro
The TCP and UDP ports that needs to be permitted in your FW rules varies according to the VC product manufacturer. For example, if you were using Tandberg (recently acquired by Cisco) the TCP and UDP ports needed to be permitted are as defined in http://www.cisco.com/en/US/docs/telepresence/infrastructure/articles/conferencing_products_conferenceme_ports_used_kb_3.shtml
Generally, the TCP and UDP ports for VC are as listed below;
TCP/389
TCP/1002
TCP/1503
TCP/1720
TCP/1024-65535 & UDP/1024-65535
UDP/1718 - 1719
Note: You could include in your ACL "deny ip any any log" on the last line, to unearth more TCP and UDP ports, assuming they are not listed above.
Sometimes, you may need to disable the default inspects too (but do this as a last resort), assuming you do see packet drops when issuing the command "show service-policy global".
policy-map global_policy
class inspection_default
no inspect h323 h225
no inspect h323 ras
no inspect skinny
no inspect sip
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Warm regards,
Ramraj Sivagnanam Sivajanam