Subject: [Sipping] Comments on draft-zhang-sipping-overlap-00.txt

From: Gonzalo Camarillo <[email-masked]>
Date: Sun, 30 Oct 2005 18:24:01 +0200

Hi,

some comments on the following draft:

http://www.ietf.org/internet-drafts/draft-zhang-sipping-overlap-00.txt

First paragraph of the introduction:

"There are two approaches of sending overlap signalling in a SIP
    network described in RFC 3578 [2]: sending the subsequent digits in a
    SIP request (e.g., INFO [3]) within an early dialog, or sending a new
    INVITE which contains all the digits received so far every time a new
    SAM is received.  RFC 3578 mainly focuses on the INVITE method and
    doesn`t address the INFO method in detail."

This paragraph in misleading. RFC 3578 states that the INFO approach has 
a number of problems, and thus, it is not recommended.

Regarding the INFO-based solution that was proposed a very long time ago 
and you are proposing again in this draft, has the disadvantage that 
does not work with regular UASs. That is, the receiver of the INVITE 
needs to understand the INFOs that follow it. If you are thinking of an 
environment where all you do is trunking between gateways and where you 
will never figure out that a service had to be applied, and was not, 
when you receive further digits, this approach could work. In a more 
general enviornment, it has serious problems.

Therefore, I would only recommend using the INFO-based approach in 
environments with the characteristics I have mentioned before.

Cheers,

Gonzalo

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From: "zhangps" <[email-masked]>
Date: Mon, 31 Oct 2005 08:18:53 +0800

Hi,??:

  ?????Gonazalo?????????????

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