Re: [Ecrit] HUM on PhoneBCP

[<[e-mail]>]

Hi Brian,
 
Please see comments inline.  
 



________________________________

	From: Brian Rosen [mailto:[e-mail]] 
	Sent: Friday, August 07, 2009 3:05 PM
	To: Liess, Laura; [e-mail]; Jesske, Roland; [e-mail]
	Cc: [e-mail]
	Subject: RE: [Ecrit] HUM on PhoneBCP
	
	

	Actually, the PIDF-LO is designed to cater for all the variations in addressing.  You don't mean "location used for emergency calls", you mean "key for location used for emergency calls".  The area code is not the location, it is a key that is mapped to PSAP URI. 
	[[LLi]]  This is correct.

	 

	  The telephone number (with its area code) is the identifier you would use with HELD to get the location,  from which LoST would get you a PSAP URI.
	[[LLi]] Here we don't use the phone number. The proxy sends the IP-address to the LIS. The LIS finds out the access hardware (DSLAM port)  corresponding to the IP-address and assigns a temporary string to it (kind of LbyR). It also finds out the phone area code for this hardware. With the phone area code, the LIS queries a table which contains the phone area codes and the corresponding PSAP URI,  then delivers the the string (LbyR) and the PSAP-URI to the SIP proxy. The SIP proxy routes the call and sends the LbyR to the PSAP. In very few cases, PSAPs dereference  the the LyBR to a civic address. 

	We do not have any kind of geo data or poligons in our database. In principle we have the the civic address, but the access to this data is quite slow.  I think other fixed networks carriers here have more or less the same. 

	 

	This seems trivial for you to implement: you deploy a HELD server that takes telephone number and returns a polygon representing the area code boundary, and you deploy a LoST server that takes that polygon and returns the PSAP URI associated with it.   
	

	  This would be no more expensive than what you are proposing.  Proxies could use this or phonebcp compatible endpoints could use it.  

	 

	NENA is planning on doing pretty much this same thing to handle legacy wireline networks where telephone number is currently the key to the location database (ALI).  The LIS will store location as the key (using held-identity), and a gateway will construct an LbyR from the phone number.  All the rest of the ecrit compatible infrastructure can then use the Location URI to get location, route, etc.

	 

	Making what you now see as a one step mapping (area code to PSAP URI) into a two step (telephone number to polygon, polygon to PSAP URI) is a bit more complex, but not any significant difference in deployment.  It also works for wireless (cell sector/ID to polygon, polygon to PSAP URI), and of course, would be upwardly compatible with real location based routing, should your systems evolve as we expect they evolve, or something like EU regulations compel more accurate location services.
	

	[[LLi]] Nobody here is willing to putting geodata or poligons into the access databases.  And we could avoid doing this just by allowing the LIS to query the local LOST with the LbyR and to deliver the PSAP URI to the SIP proxy.  

	 

	Kind regards

	Laura

	 

	Brian

	 

	From: [e-mail] [mailto:[e-mail]] On Behalf Of [e-mail]
	Sent: Friday, August 07, 2009 7:59 AM
	To: [e-mail]; [e-mail]; [e-mail]
	Cc: [e-mail]
	Subject: Re: [Ecrit] HUM on PhoneBCP

	 

	 

	Hi Martin,  

	Hi Laura,

		 

		I regard it as a goal of ECRIT - as derived from the goals of the IETF generally - to define a structure that will allow an Internet capable device to connect to a network anywhere in the world and be able to make emergency calls. Just as FTP, email protocols, SIP and etc. all work regardless of which network the devices attach to. I don't understand how the kind of variations that you are requesting be added to the specification will allow that to occur.

		[[LLi]] This is fine and usefull. Just that every country uses today different formats for the location used for emergency calls. Changing this will take time and costs money. 

		What is the harm in allowing ECs to work with local location formats which are understood only by the LIS and the PSAP ?. I dont see why a common location format must be implemented by everybody. 

		Maybe the EC could work like this : 

		*	The proxy discovers the LIS based on EDs IP-address using reverse-DNS and SRV record (this is possible with "identity extenssions") 

		*	It retrieves the location ( e.g. using HELD) in a local format understood only by the LIS and the PSAP, which are in the same country. The location is just a string which is passed transparently through the network to the PSAP. In my opinion, it would be in principle  posible to use LbyR to transport local location identidfiers, e. g.  [e-mail] , but this is currently my personal opinion, I didn' found any statemant or example in the drafts.    
		*	The LIS delivers, together with the LbyR above, the PSAP URI.  As far as I know there is currently no way to do this in HELD (or did I miss something?).        
			  

		It would be an alternative which is interoperable and quite easy to implement, without the need for the operators to change their location databases. I think by allowing this scenario, interoperable EC could be achieved earlier. And this does not exclude the scenario described in the framework and phone-bcp, where the EDs retrieve deo or civic location, which is needed for EC to work in private/enterprise networks.  
		  

		    

		 

		The position appears to be that the German regulator doesn't require anything - and the operators will not be proactive in following a specification if it doesn't include what already exists. In that context, I don't understand why there is a need for the BCP at all. There may be no need to endorse it but, similarly, there should be no need to object to it - since the operators will only put in place their preferred version of the service in any case. 
		[[LLi]]  This is not quite true. We have to ensure that EC works for different AN- and VoIP-provider and for nomadic users in Germany by 2013. Our current solution does not allow this and there is the same for other carriers. We definitively need to define in Germany an architecture which fullfills this requirements. It would be very usefull if we can use standard protocols. But nobody will be willing to change everything at once.  Having a standard based architecture which is low cost would be a great advantage. 

		 

		Kind regards

		Laura     

		 

		 That's OK... insofar as it just means German networks aren't ECRIT compatible - "compatibility" isn't a worthy goal in and of itself; it has to actually mean any device can work anywhere.

		 

		Cheers,

		Martin

		 

________________________________

		From: [e-mail] [mailto:[e-mail]] 
		Sent: Friday, 7 August 2009 12:29 AM
		To: Dawson, Martin; [e-mail]; [e-mail]
		Cc: [e-mail]
		Subject: RE: [Ecrit] HUM on PhoneBCP

		 

		Hi Martin, 

		 

		See comments inline [[LLi]].

		 

		 

		Laura

			From: [e-mail] [mailto:[e-mail]] On Behalf Of Dawson, Martin
			Sent: Wednesday, August 05, 2009 11:00 AM
			To: Jesske, Roland; [e-mail]
			Subject: Re: [Ecrit] HUM on PhoneBCP

			Hi Roland,

			 

			I think what you're saying is that you don't think that Germany will go on to implement full ECRIT support but will peg development at an interim phase. 
			[[LLi]]  We don't know how the realtime application networks or EC will look like in 20 years. Roland's answer only applies to the next 5 to 10 years. 

			 

			 That would be disappointing - not least because full ECRIT compliance would ultimately decrease the overhead associated with emergency service support for operators as well as providing a more universal service.
			
			[[LLi]]  This may be true for "green field" ISPs and VSPs but not for incumbent carriers with existing infrastructure.  And universal service is not a requirement for us. Neither the German regulator requires it nor is it a busines case.   

			 

			Nevertheless, I don't think that decision invalidates the BCP; 
			[[LLi]]  We think it does, because some of the requirements are not flexible enough to cover the deployments within the next years.  The BCP should be more flexible:  

			*	Allow additional location identifiers  

			*	Allow AN operated LOST 

			*	Provide a way to enable LOST-query based on national or domain-specific location identifier. One posiblility is to allow the LIS to query the LOST , but there are also other alternatives.  

			*	Allow and describe also network-centric, not only ED-centric architectures. If I  remember correctly, John Medland from BT also recomended to use a more network- centric architecture, at least for the next years. 

			 

			I think it just means that the German regulator and technical advisory committees would point out the subset aspects of compliance that would be applicable to that jurisdiction.  
			[[LLi]]  Again, the draft is not flexible enough for it.  If the BCP contains requirements which are not realistic, people will just discard the BCP and implement proprietary stuff. My expectation from a standard body is to define protocols and architecture which people are willing to implement in their network or products , not only in the lab.

			 

			[[LLi]]  

			We are not against the draft in principle. ECRIT provides  us with very valuable specifications as LbyR, HELD, identity extensions. But targeting an architecture which requires everbody to invest without a business case will not help the draft in the end, also if it becomes a BCP.  It would make sense to make it more flexible so people are willing to adopt it.    

			 

			 Actually, based on your description below, the NENA i2 architecture would probably be a more straightforward baseline for analysis - as has been done in the UK and Canada. Of course, it's generally recognized as only an interim step, even in those jurisdictions.

			Other comments below.

			 

			Cheers,

			Martin

			 

________________________________

			From: [e-mail] [mailto:[e-mail]] On Behalf Of [e-mail]
			Sent: Wednesday, 5 August 2009 6:19 PM
			To: [e-mail]
			Subject: Re: [Ecrit] HUM on PhoneBCP

			 

			 

			Dear all, 
			We would like the document to become a BCP as soon as possible so the group can move on with other documents related to emergency calling based on location-by-reference and ED's IP-address. 

			[[MCD]] I think you might mean "identity extensions" rather than location-by-reference because LbyR still requires the ED to obtain the reference - e.g. by HELD.
			[[LLi]] We use both, the IP-address as UE identity and LbyR. The SIP-proxy uses the IP-address to query the LIS using HTTP (it's not HELD but SOAP over HTTP, but anyway similar). The LIS responds with a numeric string associated to the caller location, in principle a LbyR and with the PSAP number. The proxy inserts the LbyR into the SIP-message (as P-Asserted-ID because the PSAPs are in PSTN) and routes the message to the PSAP.  It's a low cost solution. 

			But we can not HUM for the current form of the document. 

			Back to the document: Some requirements are far form being realistic, at least in Germany, some are not realistic at all. Implementing these requirements cost a carrier a lot of money and there is no ROI for it. 

			Just a few examples: 

			·       Requiring either geo or civic location does not provide carriers with enough flexibility to reuse their existing mechanisms and location databases. Routing of emergency calls is currently done in Germany based on phone area code not on geo or civic location, at least for the fixed network. For mobile networks the cell-id is used in common. This is regulated by the german regulator. 

			[[MCD]] How many unique PSAP routes are required in Germany? The US has lots (6000 plus) and Australia has two (and they are redundant so it doesn't matter which one). Presumably geographic information, for PSAP catchment areas, is the basis for determining which area codes are relevant to begin with? After all, an area code is not intrinsically geographic; it's a network routing value. If so, then some geographic discriminator is already in play in terms of constructing the area code based routing data (something like zip codes perhaps?) - and in that case, it should be straightforward to by-pass the area code step in the construction of routing that goes the correct PSAP URI. 
			[[LLi]] Currently, fixed networks carriers in Germany route the ECs based only on the caller's area code. Sometime in the past, the carriers, the regulator and the PSAPs operators (police, the Red Cross) agreed to do so. This may change in the future, but it will take a quite long time.      

			 With nomadic VoIP devices (and it's no good being in denial about this being the norm in the future) area code is no more reliable than it is for conventional mobile phones. And, presumably, area code is not used for conventional cellular emergency call routing?
			[[LLi]]  As far as I know, mobile networks use the Cell-ID, not the area code, and have a different table than the fixed network operators. They are not going to change this.  As to the nomadic SIP-users...if we like it or not, very few of our customers use our SIP service nomadic, let alone call EC from their laptop.         

			1              LOST as a national, let alone as a global directory is not going to be implemented. The regulator will provide in the web a static table which contains the PSAPs and the area for which they are responsible (one or more area codes). Every carrier has to implement its own routing database for emergency calls. 

				[[MCD]] Whatever the carriers implement (and they have to implement something) could just as readily be done using LoST. Then visiting devices, with no association with any local VoIP proxy server would still be able to determine a route to the correct PSAP. Alternatively, as long as the regulator is maintaining a web service with the routing information, why not make that directly accessible using LoST and save the operators the cost of duplicating the service at all?
				[[LLi]]  There is a big difference between maintaining a web page with a table which operator can print and implement in their darabases and operating a database which is queried for every emergency call in Germany, must have an availablity of 99,99...% ,  is secure enough...you know. The regulator will not do this.

				
				2       We have no intention to rely on end devices for location information because: 
				·       ED provided location info is not trusted 

			[[MCD]] Location by reference mitigates this trust issue. The emergency network can (automatically and before human resources are engaged) assess the source of the reference, and the validity of the location by dereference, without having to trust location provided directly from the ED. There are more sophisticated approaches to trustability even using LbyV - based on digital signatures across appropriate attributes. This WG and Geopriv haven't really got to grips with that... yet.
			[[LLi]]  We build the SIP-network and EC now. ED-provided location is needed if EC must work for private and enterprise networks and VPNs.  We have no such regulatory requirements.  And we don't know of any verdor of DSL-EDs which provides today SIP with LbyR and is as cheap as the devices without it. If you do, please let me know. 

			The regulator ask us to guarantee that EC works. What if a customer dials 112 and his end device does not send the location? So I have to implement both solutions, with and without ED provided location, anyway.  
			1       There are already a lot of existing EDs in usage which don't send location.    

			[[MCD]] Quite right. ECRIT doesn't overly concern itself with that interim situation. The UK and Canadian definitions for an interim solution (limiting service to in-country VoIP proxy operators) both assume third-party query via identity-extension to allow the proxy or the VPC to make the query to the LIS. This isn't extensible to universal emergency service access by all visiting devices but it does put the necessary LIS functionality in place as a very good starting point.  It would be a pity if Germany were to cease the evolution there as it would not fulfil the real promise of the Internet and the ECRIT model. 
			[[LLi]]  I wonder who will drive and pay for upgrading the interim solutions.  Unfortunatelly, it's all about money...

			 Think about it; all the complexity of putting location determination infrastructure in place for the purposes of dispatch is done - and then the next, simpler step, of using that to support the routing procedure isn't taken... that would be a waste.
			
			[[LLi]]  Do you think this is an argument for a product manager? They need a business case.  

			 

			 

			  We don't intend to require our ED-vendors to provide location because it is useless to us.   

			We could agree with the document with following changes: 

				*	Other location identifiers then geo or civil are allowed. It must be possibe that the data foermat is flexible due to different requirements from regulators over the whole world. (e.G Germany area codes for fixed- and Cell-Id for moile- providers) 
				*	The MUST for the end devices to support location information, DHCP location options and HELD shall be removed 
				*	It must be possible for the VoIP-provider's proxy to use a LOST (or an ESRP) provided by the AN or by other local provider on behalf of the AN.  

			 

			 There is no value in Hum-ing documents which one is not going to implement and does not fit into regulated schemes like in Germany. Currently, neither the IETF- nor the 3GPP-architecture for emergency calling covers our real needs for the next 2 to 5 years and in the end everybody still has its own proprietary implementation.    

			Best regards 

			Roland 

			 

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