Telcordia LERG Routing Guide
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The Telcordia LERG Routing Guide, commonly known as "The LERG," is a comprehensive data product produced monthly by the Telcordia Routing Administration(TRA) and primarily used by telecommunications service providers operating within the North American Numbering Plan (NANP) (i.e. World Zone 1). Its data supports the current local exchange network within the NANP and identifies reported planned changes in the network. The acronym "LERG" stands for "Local Exchange Routing Guide".
The LERG Routing Guide provides data to support:
- Routing of calls by service providers over the Public Switched Telephone Network (PSTN) and interconnection points of the PSTN with the Internet Protocol (IP) world
- A wide range of business needs of companies that require information about the network, numbering and other data in the product
The LERG Routing Guide includes:
- Operating Company Numbers, Company Names, Routing Contacts
- Country Code Assignments
- Numbering Plan Area (NPA) Assignments (also known as Area Codes)
- Local access and transport area (LATA) Codes By Region
- Destination Codes (NPA NXX Thousands-Blocks)
- Access Tandem Codes
- Oddball NXXs (e.g. 911, 976)
- Switching Entity Record detail (e.g. Equipment Type, V&H Coordinates), including PSTN and IP network elements
- Rate Center details (e.g. V&H Coordinates) and Localities (includes County of Localities)
- Switch Homing Arrangements (tandem and other switch-to-switch interconnections)
- Operator Access Tandem Codes (ATCs)
- Location Routing Numbers (LRNs)
