Similar means 0500 and 0808 NOT 0300 or 0700 but saying "similar" isn't terribly helpful to anyone!!
We also believe that a free number should be just that, so all 0800 and similar numbers really are free.
So many odd replies on here!
03 numbers were introduced by Ofcom as a non-geographic alternative to chargeable 08 numbers such as 0870. Calls to 03 numbers cost the same as calls to standard geographic numbers (i.e. those beginning 01 or 02).
Unlike any other non geographic number range, calls to 03 numbers must also be included in any inclusive call minute packages or discount schemes offered by fixed and mobile network operators and from payphones.
Revenue sharing is specifically disallowed on 03 numbers. 030 numbers are designated for use only by public bodies and non profit organisations. A list of organisations eligible for allocation of 0300 numbers is published on the Ofcom website.