Subject: [Enum] question on call flows

From: [email-masked]
Date: Wed, 20 Dec 2000 15:58:56 +0100

Hi steven and all,

in the ip to pstn example of the call flow, you used :
- enum to resolve number to tel uri
and
- trip front end protocol to resolve tel uri to ip address of the gateway.
Do you thing it will be possible to use enum to resolve directly number to sip:number@gateway to avoid the extra time. I though the tier 2 or the tier 3 should be able to do such resolution.

And will it be possible to detail the various tiers in the call flows, I think it will avoid some confusion amoung readers of the drafts.
thanks
fx

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From: Jonathan Rosenberg <[email-masked]>
Date: Thu, 21 Dec 2000 02:02:54 -0500

> -----Original Message-----
> From: [email-masked]
> [mailto:[email-masked]]
> Sent: Wednesday, December 20, 2000 9:59 AM
> To: [email-masked]; [email-masked]
> Subject: [Enum] question on call flows
> 
> 
> 
> 
> Hi steven and all,
> 
> Do you thing it will be possible to use enum to resolve 
> directly number to sip:number@gateway to avoid the extra 
> time. I though the tier 2 or the tier 3 should be able to do 
> such resolution.

This is a frequently asked question.

You can find discussions in the archives; there is also discussion in the
TRIP framework document:

http://www.ietf.org/rfc/rfc2871.txt

To summarize, ENUM is a *name to address* mapping solution, whereas TRIP is
an *address to route* mapping solution. These are vastly different, just as
directory protocols are different from routing protocols. Why? Because the
answer of "which gateway to go to" in the routing case depends on who is
asking, and that is not something you can do with a database protocol like
enum. Each VoIP provider will have differing relationships with various
other gateway providers, and so the decision about which gateway to use to
terminate a call is a matter of local policy. 

-Jonathan R.
---
Jonathan D. Rosenberg                       72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
[email-masked]                     FAX:   (973) 952-5050
http://www.cs.columbia.edu/~jdrosen         PHONE: (973) 952-5000
http://www.dynamicsoft.com

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From: [email-masked]
Date: Thu, 21 Dec 2000 10:03:40 +0100

yes, i agree with your statement but i wanted to know if it was also correct to return the sip uri instead of the tel uri.
I have a subscription to a french itsp and  i want him to handle my calls because he knows how to handle them.
So the tier 1 point to my itsp and my itsp's gateway or sip server knows what to do with my calls with or without using trip.
fx

Jonathan Rosenberg <[email-masked]> on 21/12/2000 08:02:54

 To:      Francois-Xavier DEROME/FR/ALCATEL@ALCATEL,          
          [email-masked], [email-masked]                        
                                                              
 cc:                                                          

 Subject: RE: [Enum] question on call flows                   

-Jonathan R.
---

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From: James Yu <[email-masked]>
Date: Thu, 21 Dec 2000 09:10:52 -0600

Yes, you can put a sip URL instead of a tel URL in the NAPTR RR.  sip URL
can also carry the telephone number at the user portion.  Your example
indicates that the French ITSP is your Tier 2 Entity (T2E).  Your T2E can
return anything you want so long as they are valid URLs (it is a service
that can be provided by a T2E).  It can return the sip URL in the NAPTR RR
with a domain name or IP address in the host portion based on some criteria.
In this case, your T2E may need to use the TRIP information to do that. 

Your T2E does not handle the call at this point yet.  It simply responds to
the DNS/ENUM query for the NAPTR RRs associated with your E.164 number.
The requestor may not need to use TRIP if no tel URL is returned in the
NAPTR RRs or the returned tel URLs are not used for call termination.

James

> Sent: Thursday, December 21, 2000 4:04 AM
> To: [email-masked]
> yes, i agree with your statement but i wanted to know if it 
> was also correct to return the sip uri instead of the tel uri.
> I have a subscription to a french itsp and  i want him to 
> handle my calls because he knows how to handle them.
> So the tier 1 point to my itsp and my itsp's gateway or sip 
> server knows what to do with my calls with or without using trip.
> fx
> 
> 
>

---

From: "Lind, Steven D, ALCOO" <[email-masked]>
Date: Thu, 21 Dec 2000 15:25:24 -0500

ENUM will return a set of URIs, one of which could be for SIP. It will be up
to whatever ENUM-enabled client you are using to select the most appropriate
URI to use. I've seen some examples where the SIP URI is <telephone
number>@<host> with a qualifier to indicate that the destination is a PSTN
device.

Steve

---------------------------------------------------------------
Steven D. Lind                   Tel: (973) 236-6787
AT&T                             Fax: (973) 236-6452  
180 Park Ave., Bldg. 2            e-mail: [email-masked]
Florham Park, NJ 07932        web: sdlind.ims.att.com         
---------------------------------------------------------------

> [SMTP:[email-masked]]
> yes, i agree with your statement but i wanted to know if it was also
> correct to return the sip uri instead of the tel uri.
> So the tier 1 point to my itsp and my itsp's gateway or sip server knows
> what to do with my calls with or without using trip.
> fx
> 
> 
>