What City has UK area code 44702 or 447031?

Any UK telephone number beginning with +44 70 in international format, or beginning with 070 in UK domestic format, is a personal "follow-me" number that can be forwarded to anywhere in the world. Note that charges to dial these numbers may be substantially higher than charges to call an ordinary landline number in the UK.

UK telephone numbers beginning with +44 74 through +44 79 (or 074 through 079) are mobile phones.

(The plus sign means "insert your international access prefix here." From a GSM mobile phone, you can enter the number in full international format, starting with the plus sign. The most common prefix is 00, but North America (USA, Canada, etc.) uses 011, Japan uses 010, Australia uses 0011, and many other countries use different prefixes.)