From: Menga, Justin (Justin.Menga@xxxxxxxxxx)
Date: Mon Nov 05 2001 - 08:03:00 GMT-3
Hi Jason,
Connection sequence for an H.323 voice call is:
1. Establish H.225 call control connection. The calling party connects to
TCP port 1720 on the called party. The parties exchange call setup messages
(similar to ISDN Q.931) and in the final call signalling message, dynamic
ports are negotiated for the H.245 control channel.
2. Establish H.245 using dynamic port.
3. Establish RTP voice channel and RTCP control channel. RTP uses any even
UDP port between 16384 and 32767, RTCP always uses the next higher (odd)
port number. E.g. the sender may choose 16384 as RTP UDP port and 16385 as
the RTCP UDP port, the receiver may choose 17000 for RTP and 17001 for
RTCP).
Firewalls in the middle need to understand H.323 versions 1 and 2 and
perform application layer inspection to determine the correct ports to allow
through.
Regards
Justin Menga CCIE#6640 CCDP CCNP+Voice+ATM MCSE+I CCSE
Network Solutions Architect
Wireless & E-Infrastructure
Compaq Computer New Zealand
DDI: +64-9-918-9381 Mobile: +64-21-349-599
mailto: justin.menga@compaq.com
web: http://www.compaq.co.nz
-----Original Message-----
From: Jason Sinclair [mailto:sinclairj@powertel.com.au]
Sent: Monday, 5 November 2001 7:59 p.m.
To: 'ccielab@groupstudy.com'
Subject: VOIP tcp and udp ports
All,
Can someone please clarify the relevant tcp and UDP ports required for VOIP?
I believe they are UDP 16384 - 16484 and TCP 1720?
Thanks
Jason Sinclair
Network Support Manager
POWERTEL Limited
Level 11, 55 Clarence Street, SYDNEY
Phone: 61-2-8264-3820
Fax: 61-2-9279-2604
Mobile: 0416 105 858
jasons@powertel.net.au
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