01800

01800 is a four-digit numeral that, in standard decimal notation, represents the integer 1800.

In telecommunications, sequences that resemble 01800 have appeared in various national numbering plans as potential toll-free or freephone designations. The exact meaning and dialing rules of 01800 vary by country and historical period; some systems have used 01-800 or similar prefixes for toll-free services, while others have used different formats entirely. Today, many regions rely on other toll-free prefixes such as 800 or 1800, and the use of 01800 may be uncommon or obsolete depending on the jurisdiction.

Beyond telephony, 01800 can function as a generic numeric string that appears in non-telecommunication contexts. It may occur as part of a model number, internal identifier, catalog code, or branding element. As with many numbers, its meaning is highly context-dependent and not tied to a single universal standard.

In numerical terms, 1800 is a composite number with prime factorization 2^3 × 3^2 × 5^2. Its divisors and arithmetic properties are standard features of the integer 1800, independent of any telecommunication use.

See also: toll-free numbers, freephone, international dialing prefixes, 1800 numbers.