Re: [Sip-implementors] [Sip] SIPit 20 survey summary

["Mark R. Lindsey" <[e-mail]>]

It is much more reasonable to expect the service-provider/enterprise  
to implement the location conveyance. They'd add the location in  
their proxies/B2BUAs/ALGs. For example, an enterprise building ALG  
could add its location before sending the call to an SP.

(Hah! Another obvious idea made un-patentable.)

In addition, it's the service provider that will likely perform SIP  
peering with a PSAP. In the US, that's the typical model in already.  
Service providers sometimes already know where their users are. Yes,  
yes, I know this isn't the main point of location-conveyance.

But besides all of this: we've got to get the PSAPs capable of  
reliably using the location provided in the call. The capability to  
send the location will be far simpler than actually having a PSAP  
that can accept and use it.






On Apr 28, 2007, at 5:19 AM, Jeroen van Bemmel wrote:

>
> Especially for the use case of emergency calls, would it not be  
> wise to
> select a much more simple approach/syntax, e.g.:
> Emergency-Location: lat=x; lon=y

The location-by-"reference" (i.e., provide a URI to a PIDF-LO instead  
of carrying the document itself) should do what you need here. Many  
UACs already have HTTP servers, which would be compatible with such a  
system, maintain end-to-end privacy requirements. Or the SUBSCRIBE- 
NOTIFY version of PIDF-LO retrieval could easily be implemented with  
a partial multipart-mime implementation, and it could work even  
through proxies.

On Apr 28, 2007, at 5:35 AM, Juha Heinanen wrote:

> another reason why it will not get implemented is that sip uas don't
> know where they are located.  gps does not work well indoors and  
> mobile
> operators at least here have refused to make public coordinates of  
> their
> base stations.

Other location-sensing technology may come along, now that there are  
good reasons for it.




Mark R. Lindsey  | ECG |  [phone]  |  [e-mail]



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