Q. What does it mean if a phone is unlocked?

A. Most phones are purchased as part of a contract with a telecoms company such as Vodafone, Three or Meteor. You sign up for a two-year contract and the phone comes as part of that contract and is locked down to the network of the telecoms provider. So if you have an iPhone from Vodafone and you put an O2 SIM card in it, it won't work. An unlocked phone will work with a SIM card from any provider and is really useful if you do a lot of travelling, particularly to Europe or Africa where local SIM cards are readily available. Using a local SIM card cuts down on call costs. There are lots of different sizes of SIM cards: mini-SIM, micro-SIM and nano-SIM, so find out which size your particular phones needs. You can purchase unlocked iPhones from the Apple online store and unlocked android phones from Google Play and Amazon.