Which UK SIM cheapest to activate from abroad just to have a UK number?

[international]

General question:

In the UK is it customary that your prepaid card remains active when you have a communication on it (send or receive a call or a text) every 6 months or so?

[NFH]

Originally Posted by international

In the UK is it customary that your prepaid card remains active when you have a communication on it (send or receive a call or a text) every 6 months or so?

Nearly all networks will deactivate the SIM card 6 months after the last change in the credit balance. Exceptions are Lycamobile (3 months) and White Mobile (2 months). In practice, most networks will also start the 6 months from the last incoming call, but this is not guaranteed by the terms and conditions. Giffgaff allows some additional ways to keep your SIM card active, making it the best SIM card for an infrequent visitor to the UK; the full list is at http://giffgaff.com/boiler-plate/terms#OurRights