Advancing IP Routing with Confidence: Using Authoritative Data to Navigate the TDM to IP Transition

The telecommunications industry is undergoing a significant transformation as networks evolve from legacy TDM infrastructures to IP-based routing. This shift creates new opportunities for efficiency and innovation while introducing added complexity, regulatory pressure and operational risk.

For Communications Service Providers (CSPs), maintaining routing accuracy and interoperability during this transition is critical. Authoritative, standardized data is emerging as a key enabler of success.

The Industry Shift: Why Now

Momentum behind all-IP interconnection continues to build, driven by a proposed December 31, 2028 timeline that may sunset legacy TDM obligations in the coming years.  Regulatory and industry developments are increasing focus on the transition from legacy TDM infrastructure to IP-based routing.

At the same time, regulators are evaluating how interconnection frameworks designed to provide support, can help evolve in an IP environment, and help assist with maintaining public safety, Next Generation 911 (NG911), and consumer protections.

Industry initiatives are also advancing IP-based interconnection models, including approaches that enable routing over the internet without traditional bilateral agreements. However, internet-based routing models remain subject to applicable legal, regulatory and commercial requirements.

Together, these forces are creating urgency and opportunity for CSPs to modernize routing strategies.

Key Challenges in the Transition

While the long-term direction is clear, for many CSPs, the transition presents several challenges:

• Increasing complexity across TDM and IP environments
• Limited visibility into IP routing availability
• Risk to call completion and interconnection accuracy, especially regarding public safety communications
• Regulatory pressure tied to modernization timelines

CSPs must continue to support hybrid environments while maintaining reliability, creating a need for consistent, trusted data that bridges both worlds.

What Stays the Same: A Familiar Routing Foundation

Despite the shift in technology, the core routing model remains largely unchanged. Both TDM and IP switching rely on shared, neutral data sources to ensure reachability, interoperability and transparency. Routing still follows a familiar process:

1. Identify the destination – which carrier or network is responsible for completing the call?
2. Check porting information – ensure the call is routed to the current serving provider.
3. Consult routing data – determine the available routing options.
4. Select the signaling path – based on the available data, commercial arrangements and network readiness.

IP introduces identifiers such as Fully Qualified Domain Names (FQDNs) and Session Initiation Protocol (SIP) URLs, but these integrate into existing provisioning and routing processes rather than replacing them. This continuity provides a stable foundation for the transition.

The Role of Authoritative Routing Data

Authoritative data is central to enabling accurate, scalable IP routing.

Platforms such as Business Integrated Routing and Rating Database System (BIRRDS) and the LERG Routing Guide support the publication of IP routing elements, including IP-capable indicators and associated FQDNs. This allows CSPs to:

• Designate number ranges as IP-capable
• Associate SIP ingress domains
• Publish standardized routing data industry-wide

These data elements can then be used for Domain Name System (DNS) routing while maintaining compatibility with legacy flows, using existing workflows without requiring new systems or APIs.

Supporting Hybrid Environments with Flexibility

Hybrid environments will remain the norm as CSPs transition to IP. Solutions such as the Alternate Route Database System (ARDS) and RouteSelect are designed to provide CSPs with the ability to publish multiple routing paths, including secondary and tertiary options, across TDM and IP.  This can support:

• Improved network resiliency
• Flexible routing strategies
• Failover preparedness

Centralized, trusted data helps simplify interconnection management while maintaining performance and reliability.

Building a Confident Path Forward

To navigate the transition, CSPs should focus on accuracy, interoperability and scalability.

Key priorities include:

• Publishing and accessing all authoritative routing data (TDM and IP data)
• Improving call completion across mixed environments
• Leveraging IP-capable number ranges and FQDN mappings
• Reducing operational risk

CSPs should also invest in flexible routing strategies that support both current and future interconnection models.

Key Takeaways

The transition to IP routing is not a reinvention of network operations, but a regulatory-driven   and industry-led evolution of existing routing principles enhanced by new technologies.

By leveraging authoritative data sources such as LERG and BIRRDS, in many environments, CSPs may be able to support more transparent, reliable and scalable routing.

With the right approach, CSPs can confidently move to IP while maintaining the performance and interoperability of their networks depend on today.

Jim Tyrrell is Vice President of Product Management with specific responsibility for TNS Communications Market.   

This article is provided for general informational purposes only and does not constitute legal, regulatory or technical advice. CSPs should evaluate applicable requirements and operational needs in consultation with their legal, regulatory, and technical advisors.