A Carrier Identification Code (CIC) is a crucial four-digit numerical code used in the public switched telephone network (PSTN) to facilitate the routing and billing of telephone calls. These codes uniquely identify the interexchange carrier (IXC) or long-distance provider selected by a caller.
Understanding CIC Codes
CIC codes are fundamental to the operation of the telecommunications network, especially for calls that traverse multiple carrier networks. They ensure that calls are directed to the correct provider and that appropriate billing and compensation agreements between carriers are maintained.
Purpose of CIC Codes
The primary functions of CIC codes include:
- Call Routing: When a subscriber dials a long-distance number, the network uses the associated CIC code to identify and route the call to the appropriate chosen carrier's network. This ensures seamless connection to the desired destination.
- Billing and Intercarrier Compensation: CICs are essential for accurate billing. They help identify which carrier originated or terminated a call, allowing for proper intercarrier compensation—the payments exchanged between telecommunications companies for carrying each other's traffic.
Format and Structure
CIC codes are structured as a series of four digits, represented in the format XXXX, where each 'X' can be any digit from 0 through 9. This simple yet effective format allows for a vast number of unique codes to be assigned to various carriers.
Types of Access Pools
To manage the allocation and use of CIC codes efficiently, separate pools are maintained depending on the type of network access:
- Feature Group B (FGB) Access: These codes are primarily used for "line side" access, typically associated with older types of service access.
- Feature Group D (FGD) Access: These codes are used for "trunk side" access, which is the more common and modern method for connecting carriers and routing traffic over high-capacity trunks.
Key Characteristics of CIC Codes
| Aspect | Description |
|---|---|
| Full Name | Carrier Identification Code |
| Function | Identifies carriers for call routing and billing within the Public Switched Telephone Network (PSTN). |
| Format | Four-digit numerical code (e.g., 1234, 0010) |
| Usage Context | Essential for long-distance and inter-carrier call processing, enabling the correct carrier to handle and bill the call. |
| Pool Management | Separate pools exist for different access types, such as Feature Group B (line side) and Feature Group D (trunk side), managed by administrative bodies like the North American Numbering Plan Administration (NANPA). |
For more information on numbering resources in North America, you can visit the NANPA website.
