Background
A workshop was held June 10 & 11 at ATIS Headquarters in Washington, DC to address a recommendation set forth in the ATIS Inter-Carrier VoIP Call Routing (IVCR) Assessment and Work Plan (February 2008). The recommendation was to conduct a workshop for inter-forum collaboration to serve as a starting point for discussions regarding evaluating a single IVCR major implementation alternative. The workshop was attended by participants from the ATIS IVCR Focus Group, ENUM LLC, 3GPP, GSMA, and IETF. At a high-level, the objective of the workshop was to determine if consensus could be reached on a single inter-carrier VoIP routing solution and begin to develop a roadmap to achieve this objective.

Workshop Outcome
Through its analysis, workshop participants concluded that in the long term, there is a desire to have a unified routing solution for the industry and standards should be developed in such a manner to support the eventual convergence of the industry solutions to a unified routing solution. Today, there are already several ENUM variations that have been implemented or will be implemented in the very near future [e.g., North American Cable Companies, GSMA/IPIA, ENUM LLC] and these will continue. However, a set of network interconnection architectures and identification of specific areas are known where standards work can simplify convergence to a unified routing solution. As for a call routing solution for the industry, Workshop participants will further analyze the Centralized Upper Tier Registry (CUTR) with respect to different scenarios for next generation carrier interconnection to determine if the CUTR model is appropriate.

• The assessment methodology will use the CUTR reference model as a routing example in order to provide a basis for analysis to determine if a unified call routing solution is suitable.
• The CUTR model provides a scalable architectural component to discover the location of routing data.
• The CUTR model supports high volume bilaterals if a unitary approach to discovering interconnect points is desired.
• The CUTR model supports multiple, diverse federation implementation approaches, e.g. CC1 ENUM LLC, IVCR Approach X, IVCR Approach Y
• The CUTR model flexibility will need to be reviewed.
• This analysis will be performed with the following caveat: as a result of this assessment, it may be determined that CUTR is not the most appropriate routing solution for the industry.

Next Steps
Workshop participants collectively agreed that in order to thoroughly analyze the CUTR model, a significant amount of work must be completed. In order to facilitate this work in an efficient manner, a Call Routing Working Group (CR-WG) will be formed. This Working Group will be represented by the participants who were involved in the IVCR Workshop and it is anticipated that it will take approximately six months to complete its efforts.

The Working Group has defined at a high-level the following steps that will be required to analyze the CUTR model as a feasible call routing solution for the industry:

1. Description of the full set of interconnect models with accompanying call flows that must be supported.
2. Description of the common data elements that must be exchanged to support the defined interconnect models
3. Performance expectations e.g. query response time
4. Flexibility and adaptability to new service requirements
5. Is an ENUM and a SIP interface required?
6. Scalability e.g. domestically/globally

The Working Group will collaboratively work on the above items primarily via virtual meetings with possible face-to-face meeting as needed. Also as needed, input and expertise may be solicited from ATIS technical committees or other industry standards development organizations.