Subject: Re: Note to Henry (Was: Re: DTMF signaling between media gateways - ouch!)

From: [email-masked]
Date: Wed, 24 Nov 1999 13:53:17 -0600

Rholm's law (providing the same functions in the same way) applies when you are
*replacing* a service.  If IP telephony and SIP are seen as a replacement for
the PSTN, it must do the same functions.  If it addresses a different need or
compliments the PSTN, it doesn't need to supply *all of* the same services.
Figure out your market and the question is answered.

My question is does the "SIP call model" align with the PSTN (or AIN) call model
well enough to support the option of replacing and/or interworking with the PSTN
services?  The catch here is defining "well enough" without limiting your market
application of the standard too severely.

Jonathan Rosenberg <[email-masked]> on 11/24/99 08:27:39 AM

To:   "Gregory D. Girard" <[email-masked]>
cc:   Pete Cordell <[email-masked]>, Henry Sinnreich
      <[email-masked]>, [email-masked] (bcc: David K
      Brown/RAC/RELTECCORP)

Subject:  Re: Note to Henry (Was: Re: DTMF signaling between media gateways -
      ouch!)

"Gregory D. Girard" wrote:
>
> Hey Pete, you hit the nail on the head in your comments below. I've done the
> analysis. I've spoken to the customers. We (Iperia) have relationships with
> all major gateway manufacturers. The message is crystal clear that SIP (Or
> its replacement/adjunct) must cover the basics before any fancy stuff even
> matters a damn to anyone anywhere. If SIP can't duplicate legacy for
> starters, it Dead on Arrival and will belong in the archives of great
> intellectual achievements that never made it commerically, right up there
> with the H.324 videophone stuff where the bottom fell out about a year ago.

Sigh...I've heard these arguments before. As I recall, the whole ATM vs.
IP debates took a similar tone... "But IP can't do QoS routing, and its
not as reliable, and it won't be fast enough, and.....". However, IP was
a success NOT because it attempted to fully replicate existing
technologies. It provided a whole new set of features and services, and
customers were more than willing to accept packet loss and delays in
exchange.

Same for cell phones. Cell phones aren't on par with landline at all.
The quality stinks, they cut out all the time. 911 doesn't even work
quite right. But, they have become immensely successful because they
brought something NEW to the table - mobility.

Same for IP telephony. We need to strike a balance. We need to be able
to do many of the most imporant PSTN services, and we *do*. Hey, we even
can do overlap dialing, for goodness sake. Your mail seems to imply that
SIP cannot do any phone feature or service, but this is just being
alarmist and is plain false. However, the aim is not to replicate the
entire PSTN feature and function set. I think that if you set down the
requirements for doing PSTN replication, you would find that the
protocols and architectures that best meet those requirements are
already done - those in use in the PSTN already. No big surprise there.
That, however, is NOT our goal. Our goal is to enable all kinds of cool
new features in IP telephony, things that just don't work at all on the
PSTN, while enabling a reasonably good set of traditional features and
services. I have already given some examples of these new services, and
there are many, **many** more. After all, why would a customer want to
purchase IP telephony service if it does nothing more than the PSTN, the
quality is lower, and the cost differential is not significant (with
declining PSTN calling rates, its a fair bet this is the case)? I
already have a phone, thank you. We're trying to build the next thing.

-Jonathan R.

--
Jonathan D. Rosenberg                       200 Executive Drive
Chief Scientist                             Suite 120
dynamicsoft                                 West Orange, NJ 07052
[email-masked]                     FAX:   (732) 741-4778
http://www.cs.columbia.edu/~jdrosen         PHONE: (732) 741-7244
http://www.dynamicsoft.com

---

From: Jonathan Rosenberg <[email-masked]>
Date: Mon, 29 Nov 1999 10:04:33 -0500

> application of the standard too severely.

In fact, a mapping of the SIP state machine to one of the IN call models
has been proposed:
http://search.ietf.org/internet-drafts/draft-gurbani-iptel-sip-to-in-00.txt

a similar draft was presented to the sip group:
http://www.softarmor.com/sipwg/meets/IETF46/drafts/draft-haerens-sip-inap-00.txt

-Jonathan R.