About CLLI Codes

character alpha-numberic code used to identify network sites, network support sites, equipment locations and related job functions. They are also ordered through the Telcordia store. The CLLI code consists of 4 main identifiers. The first four digits are an abbreviation for the city it is located in. The fifth and sixth digits identify the state it is located in. The seventh and eighth digits identify the building it is located in. The last three digits identify the type of switch or equipment.

Learning how to read the basic types of CLLI codes is very helpful in identifying routing arrangements and when assigning trunk numbers (TCICs). Below are a few helpful hints on how to identify certain types of offices.

• When the last character of the code is the letter T, the switch is used as a tandem.
• When the last three letters of the code end in RS, followed by a number, it is a remote switch that is connected to a host.
• When you see two or more offices with the first 8 digits exactly the same, (example: SNFCCA21) it means that there is more than one switch located in the building. This is important to know when assigning trunk numbers (TCICs).
• When the last three characters of the code are DS, followed by a number, it is a digital switch that may have one or more switches in the office. The number that follows identifies the number assigned to that particular switch. DS0 is always assigned first, followed by DS1, DS2 and so on.

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