[Kamailio-Users] Anyone doing CNAM lookups?

[Klaus Darilion]

Brian McCrary schrieb:
> On Thu, Oct 23, 2008 at 07:02:38AM +0200, Klaus Darilion wrote:
> 
> Hello Klaus,
> 
>> If you need to trigger SUBSCRIBE you would need the pua module. You 
>> would need to write a new module which either sends SUBSCRIBE directly 
>> (via tm module) or which links into pua module (which support 
>> SUBSCRIBE/NOTIFY in a generic ways).
> 
> Thanks for your response!  I was not aware of the pua module.  It looks 
> like it would be a good starting point, especially with it's database 
> functions.  I think I need to get to work today in setting up a new test 
> server so I can play with these new modules and see what changes need to 
> be made.
> 
>> Do you have a specification of the CNAM lookup (Event: type, payload ...)
>>
>> I am not used to CNAM (does not exist in Europe) - how does it work? Do 
>> you query the CNAM database during call setup - thus delaying the call 
>> setup until you got the answer from the lookup? Or is this an 
>> asynchronous mechanism?
> 
> Yes, I will post the information I have from Verisign on how it works (a
> little lengthy but it does a good job of describing it).  The idea is
> indeed to query the database during call setup, and wait for the answer. 
> Then the lookup would be forwarded to the SIP phone, ideally in the From
> field or P-Asserted Identity giving the called party the name of who is 
> calling them.

If the INVITE needs to get blocked during the lookup (to wait for the 
name) I wonder why the lookup is done asynchronous. IMO a simple HTTP 
request would be more efficient.

Of course if the INVITE is forward immediately and once the lookup 
finished an UPDATE with the CNAME is sent, then this sounds useful. But 
generating UPDATEs would require a B2BUA.

In general I think this is not easy to achieve with Kamailio as you have 
to delay the INVITE till the NOTIFY is received. Due to the Kamailio 
architecture this will easily block all Kamailio processes and thus 
Kamailio can not process the NOTIFYs anymore.


regards
klaus



   --SUBSCRIBEt-->

> This info taken from the Verisign manual:
> 
> IP CNAM Connectivity
> --------------------
> VeriSign's IP CNAM connectivity option provides IP access to calling
> name databases using the services of the Session Initiation Protocol
> (SIP). How IP CNAM Works CNAM Subscribers in the network can subscribe
> to CNAM Notifiers' name services on a per call basis. The CNAM Notifiers
> can broker those calling name subscriptions to either SS7-resident
> databases or IP-resident databases.  The CNAM Notifiers, acting on
> behalf of the name databases, can send a notification when those calling
> name subscriptions are resolved into the name availability indicator,
> calling name, if present, and permanent privacy status associated with
> the calling directory number. 
> 
> If the name is not to be delivered to the called end-user equipment
> because of a 'private' privacy status associated with the name, a 'From'
> header display-name parameter with a value of 'private' is sent to the
> called end-user equipment. If the name availability indicator reveals
> that the name is not available for delivery, a 'From' header
> display-name parameter with a value of 'out-of-area/unavailable' is sent
> to the called end-user equipment. Otherwise, a 'From' header
> display-name parameter containing the derived calling name is sent to
> the called end-user equipment. 
> 
> Node Behavior
> -------------
> This section describes how the CNAM subscriber and CNAM Notifier 
> functions.
> 
> CNAM Subscriber Behavior
> 
> To achieve carrier-grade availability and optimal transaction rates, the
> CNAM Notifier is optimized to support stateless fetch transactions. When
> the subscribe request is transmitted by a CNAM Subscriber to a CNAM
> Notifier, this requirement translates to the 'Expires' header having a
> value of zero (0) or, alternatively, a subscribe request with no
> 'Expires' header present, which implies the default value of zero (0) as
> defined by the 'calling-name-info'  event package [2]. This use of
> subscribe polling reduces the complexity of the calling name event,
> limiting the duration of the subscription to a single calling name fetch
> and avoiding the necessity to support state related procedures such as
> unsubscribing and refreshing subscriptions.
> 
> The Request URI of a subscribe request contains enough information to
> route the request to the appropriate CNAM Notifier, as listed in the
> request routing procedures outlined in SIP. For example, a SIP URI
> populated with the fully qualified domain name (FQDN) of the VeriSign
> Calling Name Gateway: sip:cnam-gateway.verisign.com. CNAM Subscribers
> must populate exactly one 'Event' header in the Subscriber request,
> indicating they are subscribing to the calling-name event ('Event:
> calling-name').1 Optionally, the CNAM Subscriber may also include within
> the 'Event' header an 'id' parameter, which contains an opaque token
> that identifies the specific calling name subscription within a SIP
> peer-to-peer dialog (e.g. 'Event:calling-name; id=2'). The CNAM Notifier
> includes this token, if present, in the corresponding Notify request.
> 
> CNAM Notifier Behavior
> 
> The CNAM Notifier confirms the Subscribe request with a final response. 
> A '200 OK' response indicates that the calling name subscription has
> been accepted and that the CNAM Subscriber is authorized to subscribe to
> the requested calling name information.
> 
> Non-200 class final responses indicate that no subscription has been
> created, and no subsequent NOTIFY response is sent. For example, if the
> responsible IP-resident or SS7-resident name database is not
> out-of-service because of temporary overload conditions, transmission
> availability, or maintenance activities. The CNAM Notifier returns a
> '503 Service Unavailable' final response, containing a 'Retry-After'
> header, which the CNAM Subscriber makes use of to throttle subsequent
> traffic to the affected CNAM Notifier.
> 
> Once accepted with a '200 OK' response, under no circumstance should a
> calling name subscription extend for any longer than the time necessary
> for automated processing, such as the time required to query or timeout
> waiting for a response from an SS7-resident calling name database.
> 
> Upon completion, regardless of the outcome, the CNAM Notifier sends a
> Notify request containing a 'Subscription-State' header with a value of
> terminated ('Subscription-State: terminated').
> 
> The CNAM Notifier must populate the 'Event' header within the Notify
> request to indicate a response to the calling name subscription ('Event:
> calling-name'). Additionally, if the 'Event' header 'id' parameter was
> received in the corresponding Subscribe request, the CNAM Notifier must
> echo that value back to the CNAM Subscriber (e.g., 'Event: calling-name;
> id=2').
> 
> If the subscription request fails due to a processing error (errors
> experienced querying SS7-resident name database), the CNAM Notifier
> immediately informs the CNAM Subscriber by returning a Notify request,
> which includes the 'calling-name-info' event package body indicating an
> 'out-of-service'  availability. Otherwise the CNAM Notifier must
> construct and send a Notify request that includes the calling name
> information (name availability, display-name if available, and permanent
> privacy status).
> 
> Event Package
> -------------
> Event Package Name
> 
> 'calling-name' is the token designated as the event identifier for the
> calling-name-info event package. Event Packet Parameters This event
> package does not define any new 'Event' header parameters.
> 
> SUBSCRIBE Body
> 
> This mandatory section of the calling-name-info event package defines
> the event body expected in Subscriber requests. The Subscribe body
> contains the calling-name-request portion of the calling-name-info event
> package, indicating address-of-record of callee and optionally the
> called party. The calling-name-request syntax is as follows:
> 
> calling-name-request = callee CRLF
> [ called CRLF ]
> callee ="Calling-Party" HCOLON addr-spec
> called ="Called-Party" HCOLON addr-spec
> addr-spec =SIP URI / SIPS URI / TEL URI
> Example:
> Calling-Party: sip: 9726840623 at cnam-subscriber;user=phone
> 
> NOTIFY Body
> 
> This mandatory section of the calling-name-info event package defines
> the event body expected in Notify requests. The Notify body contains the
> calling-name-response portion of the calling-name-info event, indicating
> the availability of the display-name, display-name if present, and the
> permanent privacy status. The syntax of the calling-name-response is as
> follows:
> 
> calling-name-response =calling-name-status CRLF
> [calling-name CRLF]
> [presentation-indicator CRLF]
> calling-name-status ="Calling-Name-Status" HCOLON 
> calling-nameavailability
> calling-name-availability ="available" / "unavailable" /
> "out-of-service"
> calling-name ="Called-party" HCOLON name-addr
> name-addr =[ display-name ] LAQUOT addr-spec RAQUOT
> display-name =* (token LWS) / quoted-string
> addr-spec =SIP URI / SIPS URI / TEL URI
> presentation-indicator ="Presentation-Indicator" HCOLON "allowed /
> "restricted"/ "toggled" / "no indication"
> 
> Examples:
> Calling-Name-Status: available
> Calling-Name: "Joe Smith" <sip:9726840623 at cnam-subscriber.com;user=phone>
> Presentation-Indicator: allowed
> 
> Message Flow Samples
> 
> In the following example, the 200 OK final response messages are omitted 
> for brevity.
> 
> A1: SUBSCRIBE Message
> 
> SUBSCRIBER sip:cnam-notifier.com SIP/2.0
> Via: SIP/2.0/UDP cnam-subscriber.com;branch=z9hG4bKnashds8
> To: <sip:cnam-notifier.com>
> From: <sip:cnam-subscriber.com>;tag=1234
> Call-ID: a84b4c76e66710
> CSeq: 314159 SUBSCRIBE
> Max-Forwards: 10
> Contact: <sip:cnam-subscriber.com>
> Expires: 0
> Event: calling-name; id=2
> Content-Type: application/calling-name-info
> Content-Length: 54
> Calling-Party:sip:9726840623 at cnam-subscriber.com;user=phone
> 
> A2: NOTIFY Message
> 
> NOTIFY sip:cnam-subcriber.com SIP/2.0
> Via: SIP/2.0/UDP cnam-notifier.com;branch=a1hB4bGnashds4
> To: <sip:cnam-subscriber.com>;tag=1234
> From: <sip:cnam-notifier.com>;tag=5678
> Call-ID: a84b4c76e66710
> CSeq: 951413 NOTIFY
> Max-Forwards: 10
> Contact: <sip:cnam-notifier.com>
> Event: calling-name; id=2
> Subscription-State: terminated
> Content-Type: application/calling-name-info
> Content-Length:130
> Calling-Name-Status: available
> Calling-Party: "Joe Smith"
> <sip:9726840623 at cnam-subscriber.com;user=phone>
> Presentation-Indicator: allowed
> 
> Brian