A circuit ID is a company-specific identifier assigned to a data or voice network between two locations. This circuit, for example a tie line

Tie line

A tie line, also known as a tie trunk, is a communication connection between extensions of a private telephone system, typically two PBXes.-References:...

, is then leased to a customer by that ID. A subscriber having an issue with a circuit contacts the telecommunications provider to provide this circuit ID for action on the designated circuit.

Telecom Circuit ID formats

The LEC

Local exchange carrier

Local Exchange Carrier is a regulatory term in telecommunications for the local telephone company.In the United States, wireline telephone companies are divided into two large categories: long distance and local...

 circuit ID's are based on Telcordia Technologies

Telcordia Technologies

Telcordia Technologies, formerly Bell Communications Research, Inc. or Bellcore, is a telecommunications research and development company based in the United States created as part of the 1982 Modification of Final Judgment that broke up American Telephone & Telegraph...

' Common Language Coding. At one time, the abbreviations were meaningful (for example, HC for hi - capacity) but the complexity of the business no longer allows for it.

XX/YYYY/000000/111/CC/SEG
prefix/service code - service code modifier/serial #/suffix/company identifier/segment name

• Prefix, set by administration areas for each company. They may or may not be based on LATA
  Local access and transport area
  Local access and transport area is a term used in U.S. telecommunications regulation. It represents a geographical area of the United States under the terms of the that precipitated the breakup of the original AT&T into the "Baby Bells" or created since that time for wireline...
  
  
• Service code, the type of service this circuit is providing
• Service code modifier, modifies the service code, often used for different billing options.
• Serial number, 6 digit numeric identifier
• Suffix, if a service has multiple legs or drops this will further identify the location.
• Company identifier, identifies the controlling LEC.
• Segment, the drop NAME for a multi - point circuit.

Example:

• 73/HCGS/123456/000/NE is a T1 Circuit by New England Telephone
• 44/AQDU/987654/000/G4 is a HDSL Circuit by G4 Telecom

Qwest

Serial number format: AA/BBBB/CCCCCCC/DDD/EE/F

• A Prefix: 1–2 alphanumeric characters. Optional.
• B Service Code/Modifier: 2–4 Characters. Required.
• C Serial Number: 1–4 digits. Required
• D Suffix: 3 character suffix to the serial number. May be required. (Rarely used)
• E CO (Company) Code: 2–4 alphabetic characters (NW, MS, PN) Required.
• F Segment: 1–3 alphanumeric characters. Optional for point to point interfaces.

Telephone Number Format: AA/BBBB/CCC/DDD/EEEE/FF/G

• A Prefix: Alphanumeric characters. Required if it exists.
• B Service Code & Modifier: 2–4 alphabetic characters. Required for non-DSL numbered circuits.
• C NPA: 3 digits. This is a required field.
• D NXX: 3 digits. This is a required field.
• E Line: 4 digits. This is a required field
• ? Extension: 1–5 alphanumeric characters. This is an optional field.
• F For states: AZ, CO, ID, MT, NM, UT, WY, alphas not accepted; convert D1 to 0001, D2 to 0002, etc.
• G Segment: 1–3 alphanumeric characters. This is an optional field. rarely used