Evolve N11 Abbreviated Dialing¶
Evolve ® N11 Abbreviated Dialing (N11) service routes calls to numbers starting with n-1-1 based on geographic location and several other routing rules.
N11 allows users to define the destination and the rules applied to determine the route whether the call is received via SIP or AIN protocol. In N11, calls can be handled through SIP 302 Redirect, Back-to-Back User Agent (B2BUA), Attended Transfer, Authorize_Termination, and Analyze_Info.
N11 includes a ready-to-use web-based user interface for easy access to all its functionality and different layouts for the various user roles to edit and prioritize the features of N11.
The N11 API is also available to allow developers to programmatically integrate N11 with network elements and systems and gives additional flexibility with how N11 is offered to customers.
Separation of Roles¶
N11 is designed for multi-tenancy with three distinct roles. These roles are Platform Owners, Service Providers, and Subscribers. Each of these roles have their own responsibilities and functions.
Platform Owners
The Platform Owner is the entity that deploys the network which runs N11. The Platform Owner is responsible for defining physical egress routes and other network specifics. Additionally, Platform Owners create and define Service Providers.
Service Providers
A Service Provider is the entity that offers N11 as a service to Subscribers. The Service Provider is responsible for defining call plans, allocating them to Subscribers, and determining the amount of customization for Subscribers.
Subscribers
Subscribers are the individuals or business entities that subscribe to the N11 service. Subscribers’ calls are routed based on the call plans designated to them by Service Providers. Subscribers may be given access to edit their own call plans.
Call Processing¶
When N11 receives an incoming call, the database is checked to verify that the called number is associated with N11. If the called number is not in the N11 database or N11 is not associated with it, the application responds with the configured No-Route Behavior.
If the called number is in the database, the application then steps through the routing engine. The called number will have one or more call plans associated with it. When a match is found, that rule is evaluated and the appropriate destination is provided in the response message. If no rule match applies to the current call, N11 attempts to use the next highest priority call plan, and if no matches are found there, N11 responds with the configured Default No-Route Behavior.
For each call plan, starting with the highest priority routing rule, N11 analyzes the match type and the criteria. If the rule match does not apply to the current call, the next rule is analyzed.
Signaling¶
N11 is deployed in the network and is designed to handle AIN and SIP signals to process call routing behavior.
The rest of this chapter details the specific call flow of various call treatments.
Note
Wireshark traces of a call flow can be viewed by clicking the link provided below the diagram.
SIP Call Treatments¶
SIP REDIRECT Method
The following diagram shows the message exchange when the SIP 302 REDIRECT connection type is selected.
SIP Attended Transfer (REFER Method)
The following diagram shows the message exchange when the Attended Transfer connection type is selected.
SIP B2BUA
The following diagram shows the message exchange when the SIP B2BUA connection type is selected.
AIN Queries and Responses¶
AIN Info_Collected
The following diagram shows the message exchange when Info_Collected is received.
AIN Info_Analyzed
The following diagram shows the message exchange when Info_Analyzed is received.
