As of Monday, mobile operators in the UK must port departing customers' numbers over to their new network within a day.
The previous limit was two days, but in July last year Ofcom ordered the porting time to be halved. Under the new rules, operators must give Porting Authorisation Codes (PACs) to departing customers immediately over the phone or within two hours at most via text message — the customer then gives that PAC to their new network.
Before the new rules came into place, some operators sent out PACs by post.
Ofcom originally wanted the whole porting process to take two hours at most, but the big UK operators successfully forced the regulator to back down.
The operator 3 has been a vocal critic of the whole UK number-porting process, pointing out that customers in other countries can take their number to a new network without having to go to their old network, who might then try to convince them not to leave, to get a PAC.