VoIP i2 Architecture Part I The IP Domain SBC – Southwest Public Safety

Interim VoIP Architecture for Enhanced Services (i2)  The Interim VoIP Architecture for Enhanced Services (i2) document was the primary source of information used to create this presentation.  This NENA STANDARD is published by National Emergency Number Association (NENA) as a guide for the designers and manufacturers of systems that are used for the purpose of processing emergency calls.

VoIP i2 Architecture  The following slide has the IP Domain graphically depicted, where you will see several functional elements and where they fit within this schema.  Click on any of the VoIP functional elements to be magically transported to a place presenting the element definition and a short explanation of how it fits in the VoIP I2 Architecture.  There is a short quiz at the end of the presentation concerning some of the components of the VoIP architecture. To proceed to the quiz section,

IP Domain PSAP E9-1-1 Selective Router(s) VoIP End Point DBMS IP domain Emergency Services Provider Network Call server/ proxy server LIS SRDB ALI DB MSAG VPC ALI DB ESGW(s) VDB ESZ RDB v1 v0 v2 v4 v5 v2 v3 v-e2 v7 v8 v4 Routing Proxy & Redirectserver(s) v6 Layer 3/Layer 7 Location Download Used for contingency routing v7 PSTN Gateway PSTN Layer 2 Location Download mechanisms RDO v9

So Sorry!  This element is not a discussion item in this particular PowerPoint show.  Information concerning only the VoIP elements in the IP domain are presented in this show.  Please return and select one of those functional elements.

VoIP Endpoint  The term VoIP endpoint is used to refer to the endpoint IP Device that is used to originate an emergency call. To return to I/P overview click here

Location Information Server  The LIS serves as a repository for location information.  Location information is in the form of civic address or geo-spatial location attributes correlated with a particular physical location.  The LIS is configured with mappings between individual location information and a logical representation of the physical locations with which they are associated. This set of associations is called a “Wiremap.”

 The “wiremap” in the LIS is assumed to be configured and maintained by the entity that provides/maintains the physical or logical access facility for endpoint equipment.  The administrator/owner of the LIS is responsible for creating and maintaining this wiremap, and for ensuring that the civic location data is MSAG-validated. Location Information Server (cont.) This might be an IT administrator for an enterprise, or an Internet Service provider or an access provider in non- enterprise/residential VoIP markets.

 A given endpoint can be associated with a physical location that is mapped to a particular address (civic or geo), and the address is downloaded from the LIS to the endpoint.  The LIS may also support assignment of a location query key, to a particular instance of an address, to support subsequent queries for the address. Location Information Server (cont.)

Validation Database  The VDB contains information that describes the current, valid civic address defined by the Emergency Services Network Provider’s MSAG.  The VDB should have the capability to receive a validation request containing a civic address consisting of data elements included in the civic Location Object ( LO and be able to determine if this civic address is a valid address.  The VDB should have the capability to receive a validation request containing a civic address consisting of data elements included in the civic Location Object ( LO) and be able to determine if this civic address is a valid address. LO

 The VDB will return a response indicating that a given LO is a valid address or an error response.  The VDB may be distributed across multiple databases, for example, with different VDB’s serving different regional areas; however, there will be one primary source of validation data for any given geographic area or address. Validation Database (cont.)

Location Object (LO) The LO is used to refer to the current position of a VoIP endpoint that originates an emergency call. The LO may be:  Geo location – latitude, longitude, elevation or floor, and the datum which identifies the coordinate system used.  Civic location – a set of objects that describe detailed street address information.

Call Server/Proxy Server  The term Call Server is used to refer to the entity in a private or public IP domain that provides service to endpoints in an emergency caller’s home domain and that works with the servers and other elements in the IP domain used to support emergency services call routing in the i2 solution.  The Call Server may use SIP (Switched Internet Protocol) or some other VoIP signaling protocol within its own serving domain.

Call Server/Proxy Server (cont.)  A proxy server primarily plays the role of routing, which means its job is to ensure that a request is sent to another entity "closer" to the targeted user.  Proxies are also useful for enforcing policy (for example, making sure a user is allowed to make a call).  A proxy interprets, and, if necessary, rewrites specific parts of a request message before forwarding.

Redirect Server/Call Relay Server  A call relay server is a redirect server that generates redirect responses to requests it receives, redirecting the client to contact an alternate set of URIs to route the call to the call center with which VoIP Service Provider has an arrangement. URIs URIs  Call Server/Proxy signals callback number as calling number/ANI for the call.

Uniform Resource Identifier  URI is an Internet element consisting of a short string of characters that conform to a certain syntax.  URI is an Internet protocol element consisting of a short string of characters that conform to a certain syntax.  The string comprises a name or address that can be used to refer to a resource. It is a fundamental component of the World Wide Web. For example, the URL is a URI that identifies a resource (Wikipedia's home page) and implies that a representation of that resource is obtainable via HTTP from a network host named

Emergency Service Zone (ESZ) Routing Data Base (RDB)  The ERDB contains routing information associated with each ESZ in a serving area. ESZ  It supports the boundary definitions for ESZs and the mapping of civic address or geospatial coordinate location information to a particular ESZ.

Emergency Service Zone Routing Data Base (cont.) For each ESZ, the ERDB contains: 1.one Emergency Services Routing Number (ESRN) associated with the primary Selective Router (SR) that serves the ESZ and 2.one routing Emergency Services Number (ESN) that uniquely identifies the ESZ in the context of that SR.

When an emergency call is originated, and location information is received from the VoIP Positioning Center (VPC), the ERDB will identify the ESZ and routing information associated with the received location information, and will provide to the VPC: 1.ESRN, 2.the routing ESN, 3.the Contingency Routing Number (CRN - if available) and optionally, 4.the administrative ESN. Emergency Service Zone Routing Data Base (cont.)

Emergency Service Zones When the response areas of the agencies are overlaid, they form geographic zones, each served by a combination of Police, Fire and EMS agencies. These Zones are called Emergency Service Zones (ESZ’s). Each ESZ contains the set of street addresses served by the agencies.

Root Discovery Operator The RDO is responsible for: maintaining and making available the identities of the key VDB and ERDB functions in the network. maintaining and making available the identities of the key VDB and ERDB functions in the network. ensuring that updated versions of the data with specific activation and expiry times are available. ensuring that updated versions of the data with specific activation and expiry times are available.

Root Discovery Operator The RDO is also responsible for: consolidating the discovery information as received by all VDB and ERDB operators, consolidating the discovery information as received by all VDB and ERDB operators, negotiating coordinated activation and expiry intervals, and negotiating coordinated activation and expiry intervals, and making this consolidated information available for access over the interface. making this consolidated information available for access over the interface.

 The VDB will return a response indicating that a given Location Object (LO) is a valid address or an error response. LO  The VDB may be distributed across multiple databases, for example, with different VDBs serving different regional areas; however, there will be one primary source of validation data for any given geographic area or address. Validation Data Base (cont.)

The VoIP Positioning Center VPC is the element that provides routing information to support the routing of VoIP emergency calls, and cooperates in delivering location information to the PSAP over the existing ALI DB infrastructure. The information provided includes:  Callback information, when available and  a Location Object or Location Key. The VPC may also receive other information about the call, such as Voice Server Provider (VSP) identification information.

The VoIP Positioning Center (cont.)  The VPC uses the received location information with other locally stored information that enables it to determine the appropriate ERDB to query for the routing instructions.  The VPC uses the received location information to request routing information from the ERDB that is associated with the caller’s location. The VPC may also obtain information from the ERDB to assist in contingency routing.

Emergency Services Gateway  The ESGW uses the routing information provided in the received call setup signaling to select the appropriate trunk (group) and proceeds to signal call setup toward the SR using the ESQK to represent the Calling Party Number/Automatic Number Identification (ANI) information.  The ESGW is the signaling and media interworking point between the IP domain and conventional trunks to the E9-1-1 SR that use either Multi-Frequency [MF] or Signaling System #7 [SS7] signaling.

 PSTN is the world's collection of interconnected voice-oriented public telephone networks, both commercial and government-owned.  PSTN is the aggregation of circuit-switching telephone networks that has evolved from the days of Alexander Graham Bell. Public Switched Telephone Network

 The following five review questions are designed to help you remember some of the important components of the IP Domain and their function within the VoIP architecture. Quick Quiz Click on the response that you feel best answers the question. The correct answer will highlight.

1. 1.The term VoIP endpoint endpoint is used to refer to: a) a)the termination point of a VoIP call. b) b)a repository for location. information. c)the c)the element that provides routing information to support the routing of VoIP emergency calls. d)the d)the endpoint IP Device that is used to originate an emergency call.

2.server 2.A server is a network element that receives requests in order to service them and sends back responses to those requests. One of these is NOT an example of a server used in SIP domains : a)proxies, b)VoIP b)VoIP Positioning Centers c)redirect c)redirect servers, d)registrars

3.The Emergency Routing Database (ERDB) 3.The Emergency Routing Database (ERDB) is the element that provides routing information to support the routing of VoIP emergency calls, and cooperates in delivering location information to the PSAP over the existing ALI DB infrastructure. a)TRUE b)FALSE The ERDB contains the routing information associated with each ESZ in a serving area. The VoIP Positioning Center (VPC) is the element that provides routing information to support the routing of VoIP emergency call. The VPC supports access to the routing data in the ERDB.

4.The VoIP Positioning Center (VPC) 4.The VoIP Positioning Center (VPC) is a key element in the VoIP architecture. The following statements are all true about the function of the VPC except for one. Which statement is not a function of the VPC? a.The VPC uses the received location information with other locally stored information that enables it to determine the appropriate ERDB to query for the routing instructions. b.The VPC uses the routing information provided in the received call setup signaling to select the appropriate trunk (group). c.If the VPC receives a Location Key, the VPC obtains the location information from the identified LIS. Emergency Services Gateway (ESGW) The Emergency Services Gateway (ESGW) uses the routing information provided in the received call setup signaling to select the appropriate trunk.

5.The Validation Database (VDB) Once queried, The VDB will return a response indicating that a given location is a valid address or reply with an error response”. 5.The Validation Database (VDB) contains information that describes the current, valid civic address space defined by the Emergency Services Network Provider’s MSAG. “ Once queried, The VDB will return a response indicating that a given location is a valid address or reply with an error response”. a)TRUE b)FALSE

The IP Domain  VoIP i2 Architecture The IP Domain is Part 1 in the VoIP i2 Architecture PowerPoint series Call Routing  See VoIP i2 Architecture Call Routing for an explanation of the basic routing of a VoIP call. Frank Abbenhaus SBC – Southwest Public Safety