In some countries. For example, all UK mobile phone numbers begin 07 (i.e. +44 7), fixed/special rate 08, and premium rate 09. But SMS also has "short codes",

In some countries. For example, all UK mobile phone numbers begin 07 (i.e. +44 7), fixed/special rate 08, and premium rate 09. But SMS also has "short codes", which is probably what's being abused here. 5 or 6 digit numbers, usually used for things like "Text 12345 to donate €2 to this charity" or "Send 'CXM' to 12345 and receive a message telling you when the next bus comes to this stop, costs 10¢". https://en.wikipedia.org/wiki/Telephone_numbers_in_the_United_Kingdom#Structure https://en.wikipedia.org/wiki/Telephone_numbers_in_the_Unite... https://en.wikipedia.org/wiki/Short_code https://en.wikipedia.org/wiki/Short_code