Media Gateway Control Requirements

Gunnar Hellstrom gunnar.hellstrom at OMNITOR.SE
Thu Apr 22 15:17:35 EDT 1999

I checked the Megaco requirements mainly from the point of view of how well
it covers gatewaying between different forms of real time text conversation
facilities. The most apparent need is between the current analogue network
based text telephones and IP text phones that are in the process of being
defined in SG16. The current textphones are working with different types of
modem-like signalling ( that all can be joined by the V.18 modem in the
gateway) while in IP networks it is T.140 carried by a data protocol.

With the current efforts in the US to arrange some kind of gateway between
land based text telephony and mobile text telephony, work in this direction
is already going on.

I found very little influence. And that might pose a question: Is Megaco
too vague, does it need to get more specific in its requirements to really
imply something?
But that might be the next step - the protocols and functions.
I want to suggest the following modifications to specifically mention the
important real time text gatewaying:
5.2 d : insert "text" together with the other media, to read "e.g. audio,
text, video, T.120 )

5.3 d : insert "text telephony" before FAX

11. Table 1. I am not sure what this table indicates. All multimedia
protocols are missing. Is it some kind of very basic mandatory media
Without really knowing, I recommend:  For ISDN, add Multi-media to the

    For Analogue, and Restricted, add Text telephony after FAX.

Insert a new section 11.2.4 ( pushing the existing down one step)
11.2.4 Trunking/Access Gateway with text telephone access ports

11.2.10 IVR Unit
Insert a requirement: IVR should never be the only way to control the MG.
Text based and web based control are important alternatives.


Gunnar Hellström

At 10:41 1999-04-19 -0400, Tom-PT Taylor wrote:
>If Megaco and SG 16 are to come up with a common Media Gateway control
>protocol, we must agree on the requirements.  I am attaching a zipped copy
>of the latest draft of the Megaco requirements document, with the hope that
>SG 16 experts will feel free to comment on it.  You can pass comments either
>to this list or to megaco at
>A version of this document will be submitted as a Delayed Contribution to
>the Santiago meeting.  Depending on the number of comments we receive, that
>version may be the attached one or a revision of it.
> <<>>
>Tom Taylor
>E-mail: taylor at  (internally Tom-PT Taylor)
>Tel.: +1 613 736 0961     (ESN 396-1490)
>FAX: same number by prior arrangement (manual answer).
>Attachment Converted: "c:\_Omnitor\Attach\"
Gunnar Hellstrom
Representing Ericsson in ITU-T

E-mail gunnar.hellstrom at
Tel +46 751 100 501
fax +46 8 556 002 06

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