port required for cisco 7902 IP Phone

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May 27th, 2008
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I am using cisco 7902 and 7940 IP Phone. But in my network, all ports are block except port 80 and port 2000. Plz, suggest me which port I am to open for IP Phone.



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Giuseppe Larosa Tue, 06/03/2008 - 11:35
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Hello Tarun,

another info needed is waht version of CCM you are using.

So how to modify your access-list: you need to permit DCHP, TFTP, TCP port 2000 the skinny protocol (SCCP) but you need also to allow communication between the IP phones and phones located on other IP subnets (the bearer channel in a VoIP communication= the voice packets). They use RTP protocol (realtime transport protocol) that is built upon UDP. RTP uses a wide range of UDP ports and its companion control protocol RTCP too.

"RTP does not have a standard TCP or UDP port on which it communicates. The only standard that it obeys is that UDP communications are done via an even port and the next higher odd port is used for RTP Control Protocol (RTCP) communications. Although there are no standards assigned, RTP is generally configured to use ports 16384-32767/UDP"

Use the following link for a complete reference of protocols involved in CCM 4.1:


please provide a feedback when you find the working configuration it may be useful.

Hope to help



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