On Tesco Mobile? You can now save £3/month by having ads on your phone

Pay-monthly and Sim-only customers with newer Android phones can download the free Tesco Mobile Xtras app, which will display adverts, news stories and deals every two to three times you unlock your phone.

Here we explain how it works and how Tesco Mobile's Sim-only deals stack up against others once the discount's factored in. See 30+ Cheap Mobile Tips for how to find the best phone tariffs and deals.

How does it work?

Every few times you unlock your phone, you'll see an advert (this shouldn't be a video, but we've had a report of one appearing – see below), an offer, or a news story from The Sun or The Times. We asked Tesco Mobile how frequently this content will appear – it told us it should be every two to three unlocks on average, which means the average smartphone user will see the ads about 25-30 times a day.

To get the £3 off your monthly bill, all you have to do is look at at least one advert a day for 21 days in a month. 'Look at' just means unlocking your phone and seeing an advert on the screen.

You don't have to click on it or interact with it in any way. You can easily dismiss it by clicking the 'X' in the top right-hand corner, and doing so won't rob you of the £3 discount. All that matters is that it's there.

And you can see whether you're on track to get your discount in any given month by opening the Xtras app.

How do I get it?

You can sign up from today if you're a Tesco Mobile pay-monthly or Sim-only customer (new or existing) with data included in your monthly tariff and an Android phone operating version 4.0 or higher. Pay-as-you-go customers can't currently get it.

Here's what to do:

• On your phone, go to the Google Play store and download the Tesco Mobile Xtras app.

• Sign up in the app, entering your age, interests and preferences to ensure the ads served up by the app are targeted to you. That's it.

What kind of content will I see?

You'll see adverts and promotions from a wide array of brands such as British Airways, McDonalds and Doritos, but you may also see news and sport stories from The Sun and The Times.

There are no gambling offers or sexually explicit or 'adult' content, so if a child uses your phone they won't be at risk of seeing anything they shouldn't.

In theory there are no video adverts and no sound. But we've had one report from an Xtras user who saw an embedded video in a Halifax advert which autoplayed when they unlocked their phone. As their phone was on silent at the time, the user couldn't confirm whether there was any accompanying sound.

We spoke to Unlockd, the technology company behind the app, and they said that the advert in question "slipped through" by mistake after being categorised incorrectly, and that they were looking into this. They added that relatively few customers had seen the advert in question, and said that neither that advert nor any other content on Xtras makes a sound.

Are the ads annoying?

We can't answer that – it depends on your personal tolerance levels when it comes to adverts. But the lack of video or noisy content (assuming mistakes like the one above aren't a regular occurrence) means it won't be as obnoxious as it could be.

Tesco Mobile customers can save £3 off their monthly bill with the Xtras app

How much data does it use?

Tesco Mobile says the app will typically use 100-120MB of data on average each month, though it could vary. But to compensate you'll be given an extra 200MB of data each month (on top of any allowances your monthly package gives you).

This means most users won't lose out and are actually likely to gain a small amount of data by using the app.

If you go abroad the app automatically pauses itself to avoid racking up huge data charges, and will only work if you connect to Wi-Fi.

And if I want to cancel?

You can cancel at any time by deleting the app – you simply won't get the monthly discount. You can reinstall the app in future if you decide to go back.

You can also pause the app for up to two hours at a time, ensuring you don't see any promotional content when you unlock your phone during that period.

Could it become available to pay-as-you-go customers or those on other networks?

Tesco Mobile told us it will review the success of the app and may possibly extend it to its pay-as-you-go customers in future.

Xtras is actually a partnership between Tesco Mobile and Australian tech company Unlockd. It's an exclusive collaboration in the UK, so there's no immediate prospect of other networks using the same app.

And what about the other type of data – my personal data?

The app developers Unlocked say any data you enter into the Xtras app (such as your age and interests) is encrypted and held securely by Unlockd. It isn't sold to or shared with anyone – not even Tesco.

If you delete the app your data is archived by Unlockd, so you can opt back in to the service quickly and easily if you decide to give it another chance.

Remember though that if you click through from an Xtras advert and enter any personal data (for example, to enter a competition), you're giving that information away to a third party which may sell it on.

Does the discount make it worth switching to Tesco Mobile?

To weigh up how much more competitive Tesco Mobile Sims are if you're able to get the £3/month off, we compared its 30-day Sim-only deals against the cheapest comparable deals (all offering 4G mobile internet) that we could find elsewhere.

How does Tesco Mobile's Xtras weigh up?

As the table shows, even with the £3/month discount factored in, Tesco Mobile's not the cheapest option if you're a heavy user. But for low users it does bring the price down to the same as the cheapest similar deal we could find (though the iD Mobile package comes with a little more data each month). And the cheapest comparable medium usage tariff (Giffgaff) is the same price as Tesco's, offering fewer minutes but more data.