Customers of both Vodafone UK and Three UK will be able to roam across both networks, so their phones will use the signal of whichever network is best at their location. This ‘access to roam’ brings better mobile coverage to 16,500 square kilometres of the country – an area roughly 10x the size of London. This development was made possible by the successful merger of the two companies in the UK to form VodafoneThree.

Who benefits from access to roam?

Customers of Vodafone UK, Three UK, VOXI, Talkmobile and Smarty can all take advantage of access to roam. All five are brands of VodafoneThree, the new company formed from the merger of Vodafone UK and Three UK.

How does access to roam work?

Access to roam is made possible by a network technology called MOCN.

MOCN? Isn’t that a kind of shoe?

You’re thinking of moccasins. MOCN stands for Multi-Operator Core Network.

So what is MOCN?

As you’ll know from our basic guide to Vodafone UK’s network, a mobile network actually consists of two broad parts. The first is the most visible part: the masts and antennas dotted across the country, also known as the radio network or radio access network (RAN). The other is the core network which consists of data centres hosting powerful servers which handle tasks such as routing data from place-to-place, billing and security.

Before MOCN, a phone with a Three UK SIM couldn’t make calls or transmit data through a Vodafone mast. The same was true for a phone with a Vodafone UK SIM and a Three mast.

That all changes with MOCN. Whether your phone has a Vodafone or a Three SIM, it will connect to either a Vodafone or a Three mast – whichever one provides the best signal in your location.

With MOCN, the Vodafone and Three core networks in the UK remain separate. What’s shared are the RANs, as well as the radio waves used by them which is known as spectrum.

Do I need to change any settings on my phone for MOCN to work?

No, you don’t need to change any settings on your device. MOCN/access to roam will work automatically. This is thanks to VodafoneThree’s dedicated MOCN servers. Running specialised software and dotted across the country, they identify Vodafone and Three UK SIMs, then automatically route their connections to the relevant core network no matter which radio network they’ve connected to. Think of these servers as helpful multilingual staffers in an airport or train station, directing travellers unfamiliar with the layout of the place to the right gate or platform so that they don’t miss their connection.

Who or what decides which signal/radio network is better?

The decision, on which network a Vodafone or Three customer’s phone will use, is made by the core network of the MOCN-enabled mast that it is connected to. VodafoneThree’s network design team have agreed an intricately weighted set of criteria for when a customer’s phone will move between networks.

From the customer’s point of view, the process will be seamless. For example, there won’t be any change in the stated name of the network as it appears in your phone’s settings or at the top of its screen.

Will it cost me any extra to use MOCN/access to roam?

Access to roam is available at no extra charge to customers of VodafoneThree’s five brands.

Where will MOCN/access to roam be available?

As of June 2025, MOCN has been enabled at 24 masts across the UK. By March 2026, 10,000 more network sites will have MOCN.

When will access to roam be available?

The roll out of access to roam has already started in the areas of the country that will gain the most benefit from it. 95% of the rollout will be complete within six years, with the entire rollout finished in eight years.

So the MOCN rollout will be complete in 2033? Why does the rollout take eight years?

Some masts can be upgraded with MOCN remotely with what is effectively a software upgrade. Others, however, will need to have new hardware fitted to them. Completing such hardware upgrades, especially in remote areas of the country, will take time.

Will network-dependent phone features, such as RCS messaging and Visual Voicemail, still work when my smartphone is using access to roam/MOCN?

Yes, any network-dependent phone features that are normally available on your usual network will still be available when your phone is connected through access to roam/MOCN.

Will VodafoneThree’s 5G Standalone (5G SA) service be available through MOCN?

For now, MOCN will provide customers with 4G and 5G Non-Standalone services. 5G SA service through MOCN is planned for the future.

Will VodafoneThree eventually have only one core network, doing away with the need for MOCN?

There will eventually be one core network, but that is many years away.

Does the Shared Rural Network (SRN) use MOCN?

SRN masts that cover areas which were previously Partial Not Spots – which is where service was only available from just one mobile provider – do use MOCN.

What happens if I have a dual-SIM phone equipped with both Vodafone and Three UK SIMs?

MOCN doesn’t affect the behaviour of a phone equipped with dual SIMs. Such a phone would use whichever network for whichever purposes you specify in its settings.

Is ‘roam to access’ the same thing as international roaming?

No, they’re not the same thing.

I’m a foreign visitor to the UK and my non-UK mobile provider has an international roaming agreement with either Vodafone or Three. Will my phone be able to use access to roam/MOCN?

MOCN wouldn’t affect the behaviour of an international visitor’s phone. Such a phone would use whichever network the customer’s home network has a roaming agreement with.