The National Numbering Plan (NNP), introduced in 1993, established a structured framework for the allocation and assignment of telephone numbers across public networks. The plan defined rules and guidelines for numbering resources, ensuring systematic distribution for various services, including international and trunk services, emergency helplines and special services like voicemail and intelligent network (IN) services. Additionally, the plan aligned with the International Telecommunication Union Standard Sector (ITU-T) recommendations to maintain global compatibility.

However, with the rapid expansion of telecommunication services and the privatisation of the sector, updating the NNP 1993 became essential. A future-ready and flexible approach was needed to accommodate both existing and anticipated services for the next 30 years. In response, the NNP 2003 was developed to address the complexities of a multi-operator, multi-service environment. It efficiently allocated numbering resources for basic, cellular mobile and emerging telecom services, ensuring uniform digit structures for seamless and user-friendly dialling.

The rapid growth of mobile services rendered some foundational assumptions of the NNP 2003 outdated, necessitating a review. For instance, although the NNP 2003 encompassed fixed-line and mobile numbering resources, it did not include location routing number (LRN), machine-to-machine (M2M), mobile country code-mobile network code and signalling point codes. To address this gap, the Telecom Regulatory Authority of India (TRAI) released recommendations on May 29, 2020, highlighting the urgent need for improved numbering resource management. The recommendations also proposed robust monitoring mechanisms and a centralised database to ensure transparent and sustainable allocation of numbering resources.

With the rapid expansion of telecommunications and the emergence of advanced technologies, the demand for these numbering resources increased, making efficient allocation essential. Recognising this, the Department of Telecommunications (DoT) referred the matter to TRAI on September 29, 2022, to address challenges in fixed-line numbering resources and the revised National Numbering Plan.

Consequently, TRAI urged DoT to provide current datasets related to fixed-line numbering resource allocation; allocation and utilisation of mobile numbering resources; short codes and number portability (LRN) codes; service control point codes; signalling point codes; and M2M numbering resources. Following extensive deliberations between both organisations, TRAI released a consultation paper on June 6, 2024. Based on stakeholder inputs and industry developments during 2024, TRAI finalised its recommendations on revising the National Numbering Plan to ensure efficient and future-ready numbering resource management in February 2025.

The features of these recommendations are…

Efficient utilisation of numbering resources

Concerns have been raised by stakeholders about the inefficient use of allocated Telecommunication Identifier (TI) resources, leading to questions about whether charges should be applied to both existing and newly allocated resources to encourage efficient utilisation. There is also a need for clarity on the suitable charging mechanism and applicable fees, if deemed necessary. Furthermore, there is ongoing discussion about imposing financial penalties on telecom service providers (TSPs) that hold a substantial percentage of unused TIs beyond a specified period. To this end, TRAI has recommended that no additional charges or financial disincentives be imposed on TI resources at this stage.

Revision of the fixed-line numbering scheme

Stakeholders have highlighted the inefficiencies in the current short distance charging area (SDCA)-based fixed-line TI scheme. Despite sufficient overall resources, this system poses shortages for individual TSPs due to fragmented allocation and underutilisation. Stakeholders emphasise the need to revise the DoT allocation criteria to enhance efficiency. They suggest utilising spare SDCA codes and unused sub-levels to meet future TI demands. There is also a call for adopting a 10-digit closed numbering scheme for fixed lines, similar to mobile numbering, and migrating to long distance charging areas (LDCA)-based TI scheme for greater flexibility. Additionally, stakeholders are seeking alternative solutions to address constraints, considering technical, regulatory and cost implications, including routing, interconnection and emergency call handling.

To effectively mitigate TI resource constraints for fixed-line services with minimal disruption, TRAI recommended migrating from the existing SDCA-based numbering scheme to a licensed service area (LSA)-based 10-digit closed numbering scheme. To implement this, all fixed-line to fixed-line calls, including local calls within the same SDCA, should be dialled using a prefix of “0” followed by the SDCA code and subscriber number, while the dialling pattern for fixed-to-mobile, mobile-to-fixed and mobile-to-mobile calls will remain unchanged. DoT may provide a six-month transition period for TSPs to implement the new scheme, with appropriate announcements programmed into fixed-line switches to inform users of the revised dialling pattern. Post-migration, TI resources generated using SDCA codes with suffix sub-levels allocated to TSPs should be utilised across the entire LSA rather than being restricted to specific SDCAs. Additional new fixed-line codes for TSP allocation can be created using spare sub-levels within SDCAs by suffixing them to respective SDCA codes or by withdrawing unutilised sub-levels assigned to TSPs and reallocating them to those in need within the LSA.

Further, stakeholders have raised concerns about the long-term availability of TIs for fixed-line services, given the current numbering scheme’s inefficiencies. They suggest implementing a 10-digit closed numbering scheme for fixed-line services, similar to mobile numbers, to optimise resource utilisation and ensure future availability. This would streamline numbering allocation, reduce fragmentation and enhance flexibility for TSPs. Additionally, they emphasise the need for a well-planned migration strategy to minimise disruption while addressing technical challenges related to routing, interconnection and emergency service handling.

TRAI has advocated for the adoption of a 10-digit fixed-line numbering scheme using a fixed-line location routing number code after the successful implementation of the LSA-based 10-digit closed numbering scheme, preferably within a maximum period of five years.

Addressing unsolicited communications and spoofing

The bulk allocation of TI resources by a few TSPs for session initiation protocol (SIP) and primary rate interface (PRI)-based services raises concerns about potential shortages, inefficient utilisation and limited availability for other service providers. To address this, stricter allocation criteria, periodic audits and the reclamation of unutilised resources are recommended to ensure fair distribution among TSPs. Further, enforcing calling line identification (CLI) authentication frameworks in line with ITU-T Q.3057 can help prevent abuse, spoofing and unauthorised use of TI resources.

In this regard, TRAI has recommended that TSPs implement the CLI authentication framework to safeguard telecommunications signalling from misuse, particularly when extending SIP/PRI trunks to non-TSP entities. Furthermore, TRAI reiterates its recommendation on the “Introduction of Calling Name Presentation (CNAP) Service in the Indian Telecommunication Network”, urging its early implementation by DoT.

Defining and managing inactive connections

Concerns have been raised regarding the lack of a clear definition for “inactive connection” in fixed-line services and the need for a specified timeframe for reusing TIs from such connections. A review of the definition for mobile services is also necessary to ensure consistency and efficient TI utilisation. Additionally, there is ongoing debate about introducing charges for existing and newly allocated TI resources to prevent hoarding and ensure optimal use. Some suggest imposing financial disincentives on TSPs that retain a high percentage of unutilised TIs beyond a specified timeframe. Furthermore, defining the minimum contiguous range of unutilised TIs that TSPs should be allowed to surrender for mobile and fixed-line services is crucial for efficient resource allocation. To address these concerns, TRAI has recommended that no mobile or fixed-line connection should be deactivated by TSPs before 90 days of non-usage. However, all inactive connections must be mandatorily deactivated after 365 days following the expiration of this 90-day period.

Optimising mobile and M2M numbering

The rapid expansion of connected devices has raised concerns about potential shortages of TI resources for M2M services. Issues include the limited availability of numbering resources, inefficient allocation mechanisms leading to underutilisation or scarcity, and the absence of a dedicated numbering framework for M2M deployments. Interoperability challenges in cross-network and global M2M communication further constrain effective implementation. To mitigate these issues, stakeholders suggested introducing dedicated M2M numbering ranges, exploring alternative identification solutions, and revising allocation policies for sustainable TI resource management. In response, TRAI has recommended that DoT implement its accepted recommendation on “Ensuring Adequate Numbering Resources for Fixed Line and Mobile Services”, so that all SIM-based M2M connections currently using the 10-digit mobile numbering series are shifted to a 13-digit numbering series for M2M communication at the earliest.

Enhancing short code allocation and utilisation

Stakeholders have raised concerns about inefficiencies in DoT’s current procedure for allocating Level-1 short codes, citing delays, inconsistent allocation criteria and underutilisation of resources. There is ongoing debate on whether these short codes should be reserved exclusively for government entities to prevent misuse and prioritise public services. Some suggested that charging for Level-1 short codes could enhance accountability and promote efficient utilisation. Additionally, stakeholders recommended periodic audits, usage-based allocation, and adoption of global best practices such as centralised regulation, tiered allocation based on usage categories and mandatory periodic reviews to reclaim unused short codes. These measures aim to ensure judicious distribution.

In response, TRAI has recommended that Level-1 short codes be allocated exclusively to government entities and that DoT conduct an annual utilisation audit. Short codes that remain inactive for 180 consecutive days or are sparingly used should be formally withdrawn based on merit in consultation with the user entities.

Conclusion

In sum, the evolving telecom landscape demands a more efficient approach to managing numbering resources. As technology advances and connectivity expands, ensuring fair allocation, preventing misuse and planning for future needs become critical. The discussions and recommendations reflect a shared goal among stakeholders – to create a telecom ecosystem that is not only secure and efficient but also adaptable to rapid advancements in the future.

Harshita Kalra