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A non-geographic number is a type of telephone number that is not linked to any specific locality. Such numbers are an alternative to the traditional 'landline' numbers that are assigned geographically using a system of location-specific area codes. Non-geographic numbers are used for various reasons, from providing flexible routing of incoming phone calls to generating revenue for paid-for services.

Non-geographic numbers were introduced to offer services that were historically unavailable on standard landline phone numbers, particularly in terms of call routing and special charging arrangements. Advertised benefits of non-geographic numbers include:

Calls to non-geographic numbers are handled in various different ways by the telephone network. In the simplest case, calls are simply forwarded to a regular geographic number and routed by the telephone exchange in the normal way. In other cases, such numbers may channel calls directly to a company’s private telephone system or VOIP service.

Developments in telecoms technology mean that advanced call routing facilities are no longer unique to non-geographic numbers with many suppliers offering the same functionality through 'virtual' geographic numbers.

Certain non-geographic number ranges might not be possible when calling from abroad of the United Kingdom. This is mostly the case with the 070 personal numbering range, the 080 freephone range and service numbers starting 084, 087 and 09.

All non-geographic numbers offer similar functionality, with the main difference being the charge levied on the caller. The major non-geographic prefixes now in use are:

0800 and 0808 numbers are free-to-caller from landlines, mobile phones and payphones alike. The organisation receiving the call pays the cost of the call.

Numbers starting with '03' are non-geographic numbers charged at standard geographic rates. Calls to these numbers cost exactly the same as calls to regular local or national landlines (those starting with 01 or 02). Regulation ensures that if a tariff offers inclusive minutes or free calls to numbers starting with 01 or 02, calls to 03 numbers must be included on exactly the same terms.

Since their introduction in 2007, these 03 numbers have been the only variety of non-geographic number whose charge is officially linked to that of geographic numbers. No provision has been made for replicating the old 'local rate' or 'national rate' prefixes, as almost all UK telephone operators now charge all landline calls at the same rate, regardless of location.

As of 2016, active 03 number prefixes are: 0300, 0301, 0302, 0303, 0306, 0330, 0331, 0332, 0333, 0343, 0344, 0345, 0370, 0371 and 0372.

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Wikipedia