Cheapest way to keep a UK mobile number using an eSIM

https://shkspr.mobi/blog/2026/04/cheapest-way-to-keep-a-uk-mobile-number-using-an-esim/

I have an old mobile phone number that I'd like to keep. I think it is registered with a bunch of services for 2FA by SMS, but I can't be sure. So I want to keep it for a couple of years just in case I need it to log on to something.

I don't want to faff around with physical SIMs, so I went looking for the cheapest way to keep my number for the longest time. There are a whole bunch of providers out there who will do low-cost monthly contracts (like Spusu), which I don't want. Similarly, there are some pure PAYG providers who require you to top-up with £10 every few months (like 1pmobile).

In the end, I went with Lyca Mobile (affiliate link). Total cost was £10 which should last indefinitely.

The process isn't particularly straightforward. Here's how it works:

First, add a PAYG SIM to your basket and select "eSIM"

Next, click the Bin icon (🗑) in the top right. You'll get this pop-up:

Select "Discard plan & add credit" - you'll return to this screen:

The minimum top-up is a tenner, so select that. From there, you can add details of your old number, its porting code, and when you want the port to take place. Then pay.

Done! You'll receive your eSIM instantly. Scan it with your phone and you'll be up and running. The phone number porting will take as long as it takes.

OK, but will Lyca let you keep a number indefinitely? Here's what they say:

How long can I keep my number for if I don’t use any of Lyca Mobile’s services?

Normally we will keep your number for 120 days if you do not use our service. However, you may also keep your Lycamobile number for up to 1 year without using our service. Just dial *139*9999# from your Lycamobile and follow the instructions on the screen. Please be aware that there will be a fixed annual fee of £15 which will be deducted from your balance.

Source

Note, their chatbot says the fixed fee is a fiver. Like all half-baked AI systems, it is wrong.

So, what does "using" consist of? This is hard to find out! I think is any chargeable event. Based on their current PAYG pricing the cheapest options are:

• Send an SMS for 23p
• Use 1MB of data for 15p.

If I'm right, you could use 1MB of data every 120 days. That would deplete your credit in about 22 years. More than long enough for me!

There you have it, I'm pretty sure that's the cheapest way to keep a UK mobile number on an eSIM. You can keep it switched off for 119 days, flick it on, send a quick message, then shut it down again.

Click the referral link to join Lyca Mobile

#eSIM #mobile #phone #sim