Subject: [Fwd: H323 RAS signalling and call signal transport address]

From: "Nagaraj Vn" <[email-masked]>
Date: Tue, 06 Apr 1999 12:53:36 -0700

Subject: H323 RAS signalling and call signal transport address
From: Nagaraj Vn <[email-masked]>
To: [email-masked]
Date: Tue, 06 Apr 1999 08:11:11 -0700

I am working on a VOIP project and looking into RAS messages defined in
H.225. My question is about the Terminal Registration with a Gatekeeper
using RRQ.

The terminal has to send the call signal Transport address in the RRQ
message. Does this mean that the terminal would be listening on the TCP
transport address and the Gatekeeper can Connect to it to establish the
2way TCP connection?  My thought is that the Terminal should be
listening on the call signal Transport address otherwise the Gatekeeper
cannot offer a terminating call to the Terminal.

If above is true, then what is the use of the callSignal Transport
address field in the RCF message sent by Gatekeeper? My initial
understanding was that the Gatekeeper will be listening on the
callSignal Transport address it sends in the RCF message to handle
incoming calls. But, TCP being a 2way connection, and if what I
mentioned in the first paragraph is true, then why should both the
gatekeeper and the terminal be listening on 2 different TCP callSignal
address?

As the terminal should always initiate the RRQ in Gatekeeper routed call
model, and the callSignal Transport address is mandatory in RRQ, the
Gatekeeper can CONNECT to this TCP address before sending RCF, if doing
preGrantedARQ, OR CONNECT to this TCP address when sending ACF OR when
Gatekeeper is ready to offer a call to the terminal.

Any comments are welcome.

Thanks