05 numbers

Numbers beginning 05 in the United Kingdom fall into 2 categories:

055 and 056 Numbers

These numbers are non-geographic, but unlike 03 numbers, they do not have uniform pricing.
This means that, depending on the operator, and on the individual number, the rate charged will vary.

055 and 056 numbers are divided into two categories:

055 xxxx xxxx Reserved for Corporate Numbering
Also, BT uses these for its business VoIP service.
056 xxxx xxxx Reserved for VoIP services and other LIECS (Location Independent Electronic Communications Services).

For more information see the pages on 055 numbers and 056 numbers.

0500 Numbers

0500 numbers are used for freephone services which were allocated before 1999.
The 0500 code is always followed by 6 digits.
Like 0800 and 0808 freephone numbers, they are free to dial from a landline, but are usually chargeable from a mobile phone.
More information on 0500 numbers can be found on the 0500 code information page.

Other freephone numbers in the United Kingdom are 0800 numbers and 0808 numbers.