This is just another variation of the Nigerian 419 fraud. Those phone numnbers are NOT UK mobile numbers, they are UK personal rate numbers, currently charged at 60p/min. Personal numbers may be used to divert calls to virtually any country in the world.
Having checked the whois registration for the Global Detours website, it gives an administrative contact phone number in Nigeria. In all probability, if you call either of the personal rate numbers your call will be answered by someone with a West African accent (maybe even the same person on both numbers), who will want you to send money for your visa application via Western Union!