Once upon a time, ringing someone involved either digging out a well-thumbed notebook, or memorising their area code and four/five/six digit landline number.
Then mobile phones arrived, with SIM cards storing hundreds of contact numbers and simplifying the process immeasurably.
However, convenience has made us rather lazy and forgetful.
Few people would be able to recite the mobile numbers of their closest friends or family members.
As a result, keeping your number is a desirable option when changing phone networks – not least for those contacts you rarely speak to but wouldn’t want to lose contact with.
Happily, industry rules and regulations mean it’s easy to transfer an existing number from one mobile network to another, even while switching from Android to iOS (or vice versa).
This is how you do it…
PAC up your troubles
Keeping your number during a change of mobile network involves acquiring a Port Authorisation Code from your current provider.
This nine-digit alphanumeric identifier is valid for 30 days, and networks are obliged to provide one free of charge on request.
PAC codes are given to a mobile phone number’s registered user, who passes it on to the new mobile network.
That authorises the new network to port the number over from their rival, in a process which can be completed within 24 hours.
Three, O2 and EE ask new customers to enter their PAC code into an online form, whereas Vodafone offer a choice between a web form or a standard-rate phone number.
The switchover generally only takes a few hours. First, your old SIM card or handset will flag up a network error message.
The replacement SIM card or handset will connect to the new network, though it may drop out and reconnect a few times before establishing a stable signal.
Text messages will follow, confirming the switchover is complete. At this point, the old SIM card can be discarded.
General advice when transferring and keeping your number
The switchover has to happen during a weekday, and it may not be possible to schedule it on a bank holiday Monday.
The changeover period might mean you’re not contactable, with callers being greeted by an Out of Service message or your voicemail.
It’s worth recording a temporary voicemail message in case the latter scenario arises, explaining why the number isn’t currently working and promising to call people back later.
You’ll also need to be in the UK and within range of a cell tower for the switchover to proceed. This isn’t the time to bag a Munro, or jet off for a long weekend in the sun.
PAC transfers rarely go wrong, so be patient if your new device or handset takes a while to connect.
Finally, if you change your mind and decide to stay with your existing network, the PAC code will automatically expire after 30 days.