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60 seconds on 'piggybacking' and which network really provides your mobile signal

Nick | Edited by Steve N

Updated 8 Feb 2017

If there are only one or two networks which give you decent mobile coverage, you may think your choice of mobile provider is limited. But it's possible to uncover hidden tariffs that operate off the same signal, but which cost much less. To help you understand who really provides a network's service, we've got a full breakdown of who 'piggybacks' on whom.

Why should I care about piggybacking? This is all about choice. If you live somewhere with poor signal, you might think your choice of provider is very restricted. But even if you can only get decent coverage with one network – O2, for example – that doesn't mean you'll be forced to remain an O2 customer for life.

Instead, you can try a provider on a virtual network. Giffgaff, for example, borrows network space from O2 and so will give you exactly the same coverage.

There are actually only four UK mobile networks – EE*, Three, O2* and Vodafone* (check signal using Ofcom's Mobile Coverage Checker). All the other providers 'piggyback' – ie, buy space from – one of these four networks. For example, Tesco and Giffgaff are on O2, Asda is on EE and TalkMobile is on Vodafone.

So use the chart below to see which providers are on the networks you want, then use comparison sites like MobilePhoneChecker*,  Billmonitor* or MoneySupermarket* to find the right tariff for you. See full tips and tricks in our guide: 30+ tips to slash your mobile bill.

OK, I understand the basics, but give me more details on exactly how 'piggybacking' works? Technically what's happening is that one company is borrowing network space from another. The official name for a company which does this, such as Giffgaff, is a Mobile Virtual Network Operator (MVNO). Catchy, huh?

Despite the long-winded name, these providers can be a lot cheaper. For example, for £15.99/mth you can get a 30-day rolling Sim from EE* which includes 500 minutes, unlimited texts and 500MB data (4G). But if you were to choose Plusnet Mobile* – which piggybacks on EE – at the time of writing you'd get 1,500 minutes, unlimited texts and a 4GB of data for just £10/mth. (See the Sim-only guide for the latest top picks.)

How do I know which providers I can choose from? To work out what alternative providers you can consider, you need to know who's piggybacking on whom. In total there are around 40 different piggybacking companies across the UK - here's a table showing who they use.

Remember – just because a network piggybacks on another, it doesn't necessarily mean a phone locked to one will work with the Sim of the other (this can be particularly the case with EE-locked handsets), so always check first. Unlocking is generally free or inexpensive, but can take up to 10 days – see the Mobile Unlocking guide.

What do I need to watch out for? There's very little to moan about but it's worth noting that while you may be getting access to a parent network, you won't get access to the perks available to those contracted directly to the parent company. Giffgaff users get access to the O2 network, for example, but don't get O2 Priority Moments.

We've heard some reports of the signal strength not being as good on MVNO networks as it is on their parent networks but Ofcom has told us it should be exactly the same. This is because it's the same network and it says other factors, such as the handset type or location, are more likely to cause signal problems.

Some MVNOs also don't offer 4G through their service (Asda Mobile doesn't, for example, but Tesco Mobile does), whereas the parent network will. This varies by network so check before signing up if data speeds are important to you.

If my signal's poor, how can I get better coverage WITHOUT switching provider? If you've consistently poor coverage at home and can't or don't want to switch to a provider on a network with better coverage, there is still a way to make clear calls via your current provider.

Two big providers have free apps that use your wi-fi instead of your phone signal - so you can still use your phone for calls and texts but you don't rely on the patchy network coverage. Three users can use ThreeinTouch and O2's is called TU Go*.

EE has also launched Wi-Fi Calling*, which doesn't need an app but is only compatible on certain phones such as the iPhone 5s and later. Android and Windows devices bought directly from EE also support it (but not those bought from other retailers, sadly).

Similarly Vodafone has Wi-Fi calling but only for those on certain plans, with a Samsung A5, S6, S6 Edge, S7 or S7 Edge bought directly from Vodafone, or any iPhone 6s, 6s Plus or SE.

Alternatively you could consider making free internet calls through what's geekily called VoIP, or ''voice over internet protocol' – for example using the Viber app on your smartphone. Check out our Free Web Calls guide for more.

What are my rights if I'm unhappy with my mobile coverage? It very much depends. Under consumer law you can cancel your mobile contract up to 14 days after you sign up (Vodafone's extended it to 30 days) but if the problem arises after that, it's tricky.

The telecoms regulator Ofcom says it expects providers to deal "fairly and sympathetically" with customers who have signal issues because of mobile network problems for example if a provider switches off a mast or there are faults with the network. In these circumstances the customer should be offered compensation or be allowed to leave the contract early without penalty.

However, if the reason for the loss of coverage is unclear or in dispute say if there's bad weather it's less clear cut. In these cases Ofcom says you have "clear rights to seek redress or a resolution" to a complaint. In the first instance complain directly to your network, and if it's not able to help then go through its official complaints procedure.

Free complaints handling company Resolver who will help you with your claim. Alternatively, you can do it yourself.

If after eight weeks the response you've got isn't up to scratch you can go through an alternative dispute resolution (ADR) scheme (Resolver can do this on your behalf, though). These are independent schemes which can investigate the complaint if they find in your favour, they can order the mobile phone provider to pay out up to £5,000 in compensation for any loss you may have suffered.

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