Smarty is a SIM-only mobile network offering one-month plans and a discount on unused data.

In the UK, Smarty is a SIM-only mobile network, owned and operated by Three as their low-cost sub-brand.

Promising “simple, honest mobile”, Smarty only offers a one-month rolling plan. Customers will pay £5/month for unlimited calls and unlimited texts, and then £1.25 per GB for mobile data usage. The plan is offered in three default packages (2GB for £7.50, 4GB for £10 and 8GB for £15) with customers receiving a discount for any data they don’t use. After discounts, the overall price you pay only depends on your data usage and is the same regardless of whichever package you choose.

At the moment, Smarty is a no-frills service so customers won’t be able to make international or premium-rate phone calls. Smarty also doesn’t yet offer international roaming, so you won’t be able to use your phone abroad when travelling to other countries.

In this article, we’ll review the Smarty mobile network, starting from their SIM-only plans and unused data discounts. We’ll then compare Smarty to rival mobile networks before looking at coverage and how you can keep your existing mobile number when moving to the network.

Pricing & Tariffs

SIM-Only Plans

Smarty’s key USP is you only “pay for the data you use”.

Smarty is a low-cost mobile network, offering one-month rolling plans with coverage from Three.

On Smarty, everyone pays a base amount of £5/month. This covers the cost of running the mobile network along with unlimited calls & unlimited texts. You’ll then pay £1.25 per GB for all of your mobile data usage (e.g. an extra £2.50 if you use 2GB of data, £5 if you use 4GB of data or £10 if you use 8GB of data).

When you initially sign up, you’ll be asked which of the following three plans you’d like to join:


The plans are named Small (with 2GB of data), Medium (with 4GB of data) and Large (with 8GB of data).

Regardless of which plan you choose, the amount you pay only depends on how much data you use. The mechanism that allows this to happen is Smarty’s unique “unused data discount”.

Unused Data Discount

At the end of each month, Smarty will calculate how much unused data there is remaining on your plan. Your “unused data discount” is calculated at the rate of £1.25 per GB (so if you have 3GB of unused data, you’ll receive a discount of £3.75 the following month).

Because of Smarty’s unused data discount, there is very little practical difference between the three plans. For instance, the following table shows a worked-out example for a customer who uses 2GB of data per month. On the Medium tariff, you’d receive a £2.50 unused data discount (so you’d pay £7.50 the following month after the unused data discount). On the Large tariff, you’d receive a £7.50 discount so would also pay £7.50 the following month for your plan.

Smarty Plan Chosen Original Monthly Cost Unused Data Discount Next Month’s Price
Small (2GB) £7.50/month No unused data discount £7.50 for 2GB data
Medium (4GB) £10/month 2GB x £1.25/GB = £2.50 discount £7.50 for 4GB data
Large (8GB) £15/month 6GB x £1.25/GB = £7.50 discount £7.50 for 8GB data

The impact of the “unused data discount” for a customer using 2GB of data per month. The result is you’ll always pay the same amount regardless of which price plan you choose.

Because of how the unused data discount works, we’d typically recommend signing up for the Large plan as this gives you much more flexibility at no extra cost.

There is no credit check required when signing up to Smarty, and payment will be taken in advance each month from your credit card or debit card.

International & Premium Rate Calls

Unfortunately, Smarty doesn’t yet allow you to make international or premium-rate phone calls. Instead, Smarty recommends the use of voice-over-IP applications such as WhatsApp, Facebook Messenger and Skype:

You can’t call abroad or premium numbers – yet.
We’re still getting international and premium calling ready. In the meantime, apps like Whatsapp are much more cost effective – only use data in your plan or over Wi-Fi.”

If you occasionally want to make international phone calls, see our in-depth guide to the best SIM cards for international calling.

Comparison to Alternatives

Small Plan

Smarty’s £7.50 Small plan comes with unlimited minutes, unlimited texts and 2GB of internet. This compares as follows against rival mobile networks:

ASDA Mobile300Unlimited1GB£7.00
Plusnet Mobile1,000Unlimited1GB£7.50
iD Mobile5005,0003GB£10.00

Medium Plan

Smarty’s £10 Medium plan comes with unlimited minutes, unlimited texts and 4GB of internet. This compares as follows against rival mobile networks:

iD Mobile5005,0003GB£10.00
ASDA Mobile800Unlimited3GB£12.00
Plusnet MobileUnlimitedUnlimited4GB£15.00

Large Plan

Smarty’s £15 Large plan comes with unlimited minutes, unlimited texts and 8GB of internet. This compares as follows against rival mobile networks:

iD Mobile2,0005,0006GB£15.00
ASDA MobileUnlimitedUnlimited8GB£20.00

For more information, see our full listing of SIM-only deals in the UK.


Smarty is a SIM-only mobile network so you’ll need to provide your own handset to use with the service. You can use any 3G or 4G smartphone providing it’s unlocked (this can either be your existing smartphone or you can buy a new SIM-free smartphone).

If you’re currently using your smartphone on another mobile network, it’s possible you may need to unlock it before you can use it on Smarty. For more information, see our guides on unlocking an iPhone and unlocking a Samsung Galaxy smartphone.

If you’re buying a new unlocked smartphone, there are a number of retailers where you can buy a SIM-free and unlocked smartphone. Our current recommendation is to buy a Moto G (this is a fantastic mid-range handset available from around £150 unlocked).

Network & Coverage

3G & 4G Coverage from Three

Smarty offers 97% population coverage using the Three network for 3G and 4G.

Smarty is a low-cost sub-brand of Three. As Three provides the underlying coverage for Smarty, customers on Smarty get the exact same coverage as customers on Three.

At the time of writing, Smarty offers 97% population coverage across the UK using Three’s 3G and 4G network. You can check the coverage in your area by entering your postcode on Smarty’s online coverage map:

Check Smarty Coverage Map ( →

Like Three, Smarty also doesn’t provide any 2G coverage. For this reason, if you have a 2G-only handset, it won’t be possible to use the Smarty service. You’ll need a handset that supports at least 3G or 4G coverage before you’re able to use a Smarty SIM card.

For more information about coverage on different mobile networks in the UK, please see our in-depth guide to mobile phone coverage in the UK.


Tethering or personal hotspot refers to the process of sharing your smartphone’s internet connection with other devices (e.g. with a laptop or tablet). It’s useful for getting your other devices connected on-the-go: perhaps sending some e-mails from your laptop or watching YouTube videos on your tablet.

Smarty allows the use of both tethering and portable hotspot. This is confirmed in the Smarty help centre:

You’re entitled to use your data however you like, no matter which of the 3 SMARTY plans you’re on. So you can tether and use your phone as a mobile hotspot with your full allowance if you want to.

For more information, see our guide to tethering on UK mobile networks to find out which other mobile networks will allow you to tether.

International Roaming

Smarty doesn’t support international roaming.

Unfortunately, Smarty doesn’t yet offer any international roaming on their service. This means customers will not be able to use their handset when travelling outside the UK.

In our opinion, the lack of international roaming is a major drawback of Smarty. Customers of most other UK mobile networks can use their phone across Europe at no extra charge. Furthermore, customers on Three’s own-brand Pay As You Go mobile network get access to Feel At Home Around The World (free roaming in 60 destinations including the USA, Australia, Brazil, Singapore and more).

If you regularly travel abroad and would like to continue using your smartphone when you’re there, we’d recommend choosing another mobile network for the time being.

Keeping Your Phone Number

It takes one working day to move your phone number to Smarty.

If you’d like to keep your existing phone number when moving to Smarty, it’s a straightforward process to do this.

To do so, you’ll need to request a PAC Code from your old mobile network. This should then be provided to Smarty, through your online account dashboard. Smarty will schedule the transfer of your phone number, normally for the next working day.

For step-by-step instructions on how to move your phone number to Smarty, please select your current mobile network from the drop-down menu below:

PAC Code Finder: Transfer Your Phone Number to Smarty

Your current network provider:

  More Options

For more information about transferring your phone number between networks, please see our guide to using a PAC Code.

More Information

For more information, please see the official Smarty website.

Your Comments 27 so far

We'd love to hear your thoughts and any questions you may have. So far, we've received 27 comments from readers. You can add your own comment here.

    • Hi Ant,
      There is no limit to the number of times they’ll refund unused data. If you were never to use any data at all, you’d just pay £5/month for unlimited calls and unlimited texts.

  • Hi Ken – Apologies if this has been mentioned elsewhere but, if the separate allocation of £5 for service,calls and texts is ignored, the £15 large plan would appear to be the best value. On the assumption that any purchase is used in full, the cost per GB equates to £3.75 for Small, £2.50 for Medium and £1.88 for Large. These figures would of course vary if any discounts are taken or extra purchases made. After all, all providers include calls and texts in plans (albeit not always unlimited), so any mention of the £5 charge can be ignored.

    • Hi Pete,
      Many thanks for your comment. I’m not sure it really makes sense to ignore the £5 allocation for unlimited calls and unlimited texts. The reason being that customers on any Smarty plan can use additional data outside of their allowance at the rate of the £1.25/GB (this is essentially the opposite of an “unused data discount”, where you pay a little bit more for data used over your base allowance). Therefore, someone on the 4GB plan costing £10/month could buy another 4GB by paying £5 (therefore taking them back up to £15 for 8GB of data). The result of this is the overall amount you pay only depends on how much data you use, and not on which of the three plans you choose.
      Saying that, it’s certainly the case that as you use more data on your plan, the overall impact of the £5/month allocation becomes a lot smaller relative to the cost of your data. For instance, if you were to use 100GB per month, you’d pay £130 for this (£1.30 per GB under your calculation above). If you were to use 1000GB per month, you’d pay £1255 (£1.255 per GB under your calculation above) and so on 🙂

      • Hi Ken thank you for your reply and point taken. However, I think that someone intending to purchase, for example, just one Small plan a month for £7.50 could mislead him/herself into thinking they are paying just £1.25 per GB for the 2 GB they receive whereas they are in fact paying £3.75 per GB with calls,texts and admin included (as with any other provider). That said, £3.75 per GB for a small plan is still good value compared with,say, GiffGaff where £7.50 will purchase just 1 GB. I do of course agree that any top ups would improve the value for money.

        • Hi Pete,
          That absolutely makes sense 🙂 I’m probably one of those people who rarely use minutes & texts these days, so your calculation is probably also more applicable to me.
          One interesting aspect of the mobile market is that people’s data usage doesn’t always increase with the size of their allowance (especially so when it gets beyond a certain point). That’s partly one reason we now see lots of deals on the market offering 20GB of data, 50GB of data or even 100GB of data (often at the £20 to £30 price point). Many people pick these tariffs are they have really good “per gigabyte” rates, though of course, they never actually use them and then end up paying more overall!

    • Hi Nikki,
      I believe the plans at Smarty are essentially “capped” (technically, it’s a Pay As You Go service and as such, you’ll need to buy a “cash add-on” for out-of-bundle usage). For this reason, it shouldn’t be possible to get an unexpected large bill – all that could happen is you’d use up the cash add-on balance.
      Hope this helps,

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