That was a question I recently asked myself. I had a spare number that I wanted to keep due to it being quite memorable and I recently went down the path of trying to figure out what are the cheapest options to store a UK number. All these options are below £2.50 a month, which means it is cheaper than most mobile plans but all of these have advantages/disadvantages. Some of the following options I have not tested personally and I would recommend conducting your own research into each option to make sure it is right for you.
Last updated: 30th August 2026
giffgaff
Terms: make a chargable activity (either use calls, texts, data, purchase plan or top up) once every 6 months. £10 minimum topup. Charges: 10p/txt, 25p/min, 10p/MB.
https://www.giffgaff.com (affiliate link1)
So let’s just be straight up. This is the one I went with and this tends to be the one that everyone suggests for low users. I do not regret my decision whatsoever going with giffgaff. Whilst it isn’t the most flexible operator for storing a number (my suggestion below is more flexible with cutoff dates), it is realistically the best choice. You will need to use a physical SIM to get started with giffgaff initially, since you now have to buy a plan when setting up an eSIM with them due to recent crackdowns against users using the services abroad for an unreasonable amount of time.
With giffgaff, their terms simply state to make a chargable call/text, use data, top up or start a plan at least once every 183 days. They give 2 warnings if you haven’t done this: one at roughly 150 days and one at roughly 176 days.
The other main advantages of giffgaff is that they do have a focus on trying to do good (e.g. they’re quite focused around the environment and are registered as a B Corp) and they have a vibrant community forum where you can get help for lots of issues at any hours of the day2. Additionally, it’s worth noting that you can earn credit for referring others to giffgaff (which may be helpful if you do need to make some calls/texts from the number you need to store) and it does work with Airtime Rewards (the option below probably does too, but it is not advertised)3. If you need to call internationally, fees are generally relatively cheap too.
VOXI
Terms: make a chargable activity (either use calls, texts, purchase plan or top up) once every 180 days. You’ll be given 90 days notice if you have not made one. £10 minimum top-up. Charges: 14p/txt, 30p/min.
This would be my main recommendation, except for one thing. I’m not sure whether you have to sign up to a plan for one month before reverting to traditional PAYG (which could mean spending £10 on a plan and then £10 on credit to be sure that you keep your number)4. This is a great option if you’re actively in the UK, since they are by far the most flexible operator for leaving a SIM inactive. Even though their terms say 270 days (worth noting that it looks like it’s 180 days for your first usage5, but thereafter, 180 days + a 90 day notice period), it’s really much more flexible than that. The number that I was actually porting came from VOXI from a student plan that was under a friend’s email and virtual card details, and it lasted an estimated 15 months without using a single penny. I’ve also heard other stories of the same.
A&A
£12 setup fee, £1.80 monthly fee. Outbound calls up to 1.5p/min (UK landline), 4p/min (UK mobile) & 3.6p/txt. Click for pricing info
My final recommendation is a VoIP provider known as Andrews and Arnold. They’re pretty well established + definitely know their stuff and they allow you to port a mobile number into them and get SIP details for it. That allows a lot of flexibility on where you can use it: you could use a softphone app on your phone for your number, link it to a VoIP phone etc. A&A are focused towards more technically minded people but this is probably a better option if you spend more time abroad or do need to make occasional calls (this is going to be your cheapest option for occasional calls and texts really, international rates are also pretty good (although there’s no international text support).
Hopefully some of the advice provided helps you find an operator to store a number with. If you found this helpful, consider sharing with others. Thank you!
Footnotes
- By using the link provided here, I may get credited by giffgaff in points that can be redeemed for cash or directly in cash for referring a user to the service if users order a physical SIM. Depending on whether my account is in the standard MGM program when using the link, you may receive bonus credit towards your account. giffgaff provides me with the first names of members who signed up using my link (as well as their username), if you are not comfortable with this, please sign up directly using this link. ↩︎
- I ended up starting to help on the forum from my previous experience elsewhere, many members of the community are friendly and even at stupid times at 3am, you’ll have someone trying to help you. ↩︎
- Listed networks for Airtime right now seems to be all the main 4 networks for Pay Monthly, main 4 + Lebara + giffgaff on Pay As You Go. VOXI should support Airtime since it is effectively a Vodafone pay as you go SIM, but it isn’t officially listed. ↩︎
- I attempted to do searches prior to publishing but couldn’t find anything certain whether you can activate without buying a plan for your first month. The FAQs on the order SIM page seem like you do need to setup a plan first before reverting to credit. I would recommend asking around just to make sure (if you’re a student, you get your first month free anyways on a VOXI plan). ↩︎
- This is information I could find regarding credit vouchers, which can be bought from stores. No idea about online. ↩︎
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