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Mobile operator Vodafone (VodafoneThree) has revealed a little bit more information about how their new “Access to roam” feature will work. This will shortly become one of the first major benefits of their recently completed merger with Three UK (here and here) – allowing 27 million customers to roam across both networks at no extra cost.
The official announcement of all this stated that the new ability would be ready “within a few months” and will “happen automatically, with no need to change a thing (phones will connect to the best coverage available)“. By the end of 2025 this will remove a total of 16,500 sq/km of not spots (areas with no mobile signal) – equivalent to 10x the size of London – with the first 25 sites already live. But this didn’t provide the full and correct context.
The service will deliver all this by harnessing a network sharing architecture known as Multi-Operator Core Network (MOCN), which allows more than one network operator to share the same Radio Access Network (RAN) – including towers, antennas, and spectrum – while maintaining separate core networks (usually situated inside data centres or similar).
In other words, whether your phone has a Vodafone or a Three UK SIM, it will connect to either a Vodafone or a Three UK mast – whichever one provides the best signal in your location. Naturally this approach has prompted a few questions from the customers of both operators and so Vodafone has now released a useful Q&A, which helps to answer a lot of those queries.
Some of the highlights of this include confirmation that it will take a total of 8 years to fully complete the roll-out of ‘Access to roam’ (it’ll be 95% complete after 6 years), which wasn’t made clear on the original announcement. The deployment is thus initially being strategically focused on areas of the country that will gain the most benefit from it (i.e. those with a poor 4G or 5G signal from one or the other operator).
In addition, while both 4G and 5G (mobile broadband) Non-Standalone networks will benefit, users of the latest 5G Standalone (5G SA) services (i.e. a pure end-to-end 5G only network) will have to wait a bit longer as it’s not yet able to support those (this is vaguely expressed as being planned for the future, with no firm ETA).
However, it’s probably best to think of “Access to roam” as being an interim technology, since eventually Vodafone and Three UK will look to have a single core network that will do away with the need for MOCN. But delivering on this is still “many years away“, which is an interesting thing to say given that MOCN itself will already be taking up to 8 years to fully deploy.
Access to roam Q&A
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.