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Author Topic: What does this circuit id mean?  (Read 34589 times)

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Offline CnGracin

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What does this circuit id mean?
« on: May 03, 2010, 04:23:23 PM »
What does this circuit id mean?

If you’re looking for a way to decode telephone company circuit identifications, I’m going to attempt to explain the format of what you’re looking at. Ckt id’s come in multiple different formats but I’ll touch on the three most common that will be seen tagged on the point of demarcation (a.k.a demarc, demark, NID, Network Interface Device, MPOE (minimum point of entry.))

First and most common is the CLCI, Special Service, Service Code format. It is formatted like this:

Prefix /Service Code +Modifier/ Serial Number //   Suffix / Segment Name
1 2    /“ 3 4”              “5 6”  / 7 8 9 10 11 12  //13 14 / “xx” (multi point only)

* Prefix - 2 alpha numeric characters: ID’s the market area (sometimes (but not always) tied to the LATA number)
* Service Code (note1): Two Alpha characters the designate the service. These two letters will tell, “what kind of circuit is this.”
* Modifier: modifies the service code. (Often billing and tariff information)
* Serial Number: Unique numeric number to identify the circuit. There is no meaning built in to the number, it’s just a serial number.
* Suffix: Alpha code that will identify the Telco in control of the circuit.
* Segment name: Alpha designation of the leg of a multipoint circuit. (Not common for this to be used.)

(Note 1: The service code will be the characters that will tell you what type of circuit it is. Keep in mind also that there are service codes for Access Circuits (cross-LATA) and non-Access Circuits (same LATA.) So one ya’ll may say, “A DH is a Hi-Cap T1 and another may say, “I thought HC was a Hi-Cap T1.” Both would be correct. DH for same LATA HC for cross-LATA.)

Example CLCI (special service circuit id:)
* The first two letters, in your example "HC" indicates 1.54 Mbps access circuit. A Hi-Cap T1...
* The "G" and the "S" operate independently to modify the service code “HC.”
GS= Interstate: The interstate usage is more than 10% interstate as determined by the "PIU" FID, or for Feature Group A services, the "UTNT" FID initially indicated more than 10% interstate usage. Customer/provider interface.

The second type circuit id I’ll mention is telephone number fixed format circuit id. It formats like this:

Prefix/service code+modifier/NPA/NXX/line number/extension or trunk/segment

* Prefix= Admin Area or Market Area designator (sometimes (but not always) tied to the LATA number)
* Service Code= Two characters representing the type of service, just like in a special service code.
* Modifier= provides additional info for the service code including % Lata usage and billing
* NPA= The area code
* NXX= The C.O. code or exchange ID
* Line Number= well, that’s the number of the line
* Extension= Not often used.
* Trunk Code= The sequential number of the trunk in the trunk group
* Segment= Drop identifier for multi-point circuits

Here’s an example for an OPX (off-premise extension) circuit:

01=Market Area
OP= Off-premise extension
NA= inter-lata with no other parameter needed (default no entry required)
555= Area Code
111= Exchange
8750= Phone number
“//” No extension or trunk code present
002= Drop two of a multi point OPX

The type I’ll mention is the CLFI (Common Language Facility identifier) circuit identification method. These are used for channelized carrier facilities.

nnn/xxx/Location 1/location 2

* nnn: Would a 1-5 alphanumeric characters that would uniquely identify the carrier facility.

* xxx would designate the Facility Type. 1-6 alphanumeric characters. Examples would be T1, T1ZF, T3, T3Z. This would show the rate based on the North American Digital Hierarchy Scale.

Location 1 would be called the “A CLLI (common language location identifier)” These codes: 8 or 11 alphanumeric characters and designate a specific location (note 2)

Location 2 would be called the “Z CLLI (common language location identifier)” These codes: 8 or 11 alphanumeric characters and designate a specific location (note 2)

(Note 2: For several years now, which is location is considered location 1 or location 2 has been determined by alphabetic order, rather than some older methods of determining ownership of the facility circuit.)

Example of a facility circuit id would be:


* 101 = A unique identifier of the circuit.
* T3Z = Identifies the carrier facility as being a T-3 with B8ZS line coding.
* DLLSTXYL = Would show location 1 being in Dallas, TX Blue Lab.
* DLLSTXBL = Would show location 2 being in Dallas, TX Riverside Exchange.
Cars -n- Guitars Racin' (Racing retired '07)

Offline CnGracin

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  • Location: O'Fallon, MO
  • Posts: 32
Re: What does this circuit id mean?
« Reply #1 on: May 03, 2010, 05:04:10 PM »
Sorry, meant to mention this on the first posting but it was long ‘nuff right?  :023:

If you happen to run across a specific circuit id that has you puzzled please log-on and and start a new topic to ask… There are several members or mods here that can help decode it for ya.  :045: Weather it be from having seen the formats and id’s a million times before or different lookup tools that are available to us not found online.
Cars -n- Guitars Racin' (Racing retired '07)