Cheapest SIM only deals

The cheapest plan on paper isn't always the cheapest for you. Work out how much data you actually use each month — most people overestimate — then look for the lowest-priced SIM that comfortably covers it.

Smaller virtual networks such as Smarty, Lebara and Giffgaff often undercut the big four for low and mid data allowances, while the major networks tend to win on unlimited tariffs.

No. Budget SIM providers usually run on the same masts as the major networks they rent capacity from, so coverage and speeds are typically identical in most areas.

It's still worth checking the network's coverage map for your home and work postcodes before committing to a cheap deal.