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Operating company number (OCN)

published · September 27, 2026

An operating company number (OCN) is the four-character code North American numbering tables use to identify the company that holds a central office code or thousands-block.

An operating company number (OCN) is the four-character code North American numbering records use to identify a telephone company. NANPA's central office code and thousands-block reports, and the Canadian administrator's code table, list every assigned code or block with its holder's OCN beside the holder's name. In NANPA's tables of 26 September 2026, 3,020 OCNs name 2,817 distinct holders: no OCN names more than one holder, while 104 holder names appear under more than one OCN, one of them under 31. OCNs mix digits and capital letters; 913 of those 3,020 contain a letter.

What Spaw answers

carrier_code is the regulator's code for the holder of the number's block: the OCN in the NANPA and CNAC tables, ARCEP's operator code in France and UKE's operator ID in Poland. In a pooled US code it is the OCN of the number's own thousands-block where NANPA lists that block. The British, Dutch, Italian, Australian, New Zealand and Mexican tables name holders without a code, so there, and wherever carrier comes from the numbering plan's prefix metadata rather than a table, carrier_code is null.

carrier_brand is matched on the OCN first and the name second, from a bundled, versioned brand map (carrier-brands in sources), because the tables list legal entities rather than the brands people know: NANPA lists OCN 6010 as NEW CINGULAR WIRELESS PCS, LLC, which answers carrier_brand "AT&T". A name the map does not know answers null; nothing is guessed.

What it does not mean

An OCN identifies the company a code or block was assigned to. After a port another company serves the number, and no open table lists that company's code against it, so carrier_code keeps naming the original holder. An OCN is also not a carrier identification code (CIC), the four-digit code NANPA assigns that is "used to route and bill calls in the public switched telephone network" (https://www.nanpa.com/numbering/carrier-identification-codes-cic, accessed 27 September 2026). How the holders of North American codes group under network brands is on the phone facts for the United States and Canada.

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More glossary

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