Customers who have reached the end of their mobile phone contract should have their phones unlocked from the network for free, says consumer group Which?
It believes that keeping phones locked prevents customer finding a better deal by switching providers.
Pay-as-you-go mobiles should not be locked at all, it said.
One mobile operator said its phones were locked to prevent fraudulent activity.
More than 200 towers now built or upgraded to 4G in quest for a minimum of 50Mbps connectivity nationwide by 2025.
British mobile phone giant Vodafone has reached an agreement with Mediaset to offer pay-TV content of the Italian broadcaster to its customers in the southern European country, the two companies said in a joint statement on Thursday.
The world's second-biggest mobile phone company Vodafone revealed government agencies in six unidentified countries use its network to listen to and record customers' calls, showing the scale of telecom eavesdropping around the world.