UK communications regulator Ofcom is investigating the current system of porting fixed and mobile telephone numbers when changing operators. 

Number portability allows subscribers to retain their telephone numbers when switching from one provider to another.

It is intended to promote competition by preventing customers from being locked into a particular provider for fear of losing an important phone number.

According to Ofcom, the system is currently implemented using 'call forwarding' which makes changing providers time consuming, and in some cases even reduces competition.

Ofcom is considering whether there is a case for mandating an alternative 'central database' implementation, which would ultimately benefit consumers but it expensive to implement and would affect different operators unevenly.

Ofcom has contracted consultancy group Sagentia to research the costs to fixed and mobile operators of changing to the central database approach. 

Sagentia looked at the costs and benefits in the light of moves by operators towards new types of network known as Next Generation Networks (NGNs).

The study found a strong case for mandating a central database for NGNs and for mobile networks, but not for the older types of fixed network as the switches used are unlikely to be capable of carrying out queries on their databases on every call.

Ofcom reckons that mobile companies should be able to move over to a central database system by September 2009, and a full transition of fixed networks should be achievable by the end of 2012.

Ofcom is also considering shortening the current port lead time, the time is takes to move a number from one provider to another, from the industry agreed five days to less than one working day.