Customers looking to transfer their mobile number to an alternative supplier should soon find the process quicker and easier.

Ofcom, the telecoms regulator, has announced new rules – to come into effect next April – under which networks will have to transfer existing mobile numbers to and from rivals in a maximum of just two days.

At present, customers wanting to retain their number have to endure a process – which includes obtaining a porting authorisation code from their current provider – that can take up to five days.

Ofcom's chief executive, Ed Richards, said: "The industry should introduce a new system that will stimulate competition and encourage customers to exercise choice between competing suppliers with a minimum of convenience." The waiting time, says Ofcom, could fall even further by 2009 to a couple of hours.

Karen Darby from price- comparison service SimplySwitch.com said: "While the current switching process is straightforward, in an age of super-fast technology it is lengthy and outdated, and adds an unnecessary stumbling block for people looking to transfer."

Rob Barnes from Moneysupermarket.com, another price-comparison service, said the networks have been making the process difficult. "Ultimately this means people are reluctant to move for fear of losing the number they have had for years."

He added: "Practically, there is no reason for porting to take so long."