Orange and T-Mobile customers have been promised faster internet access on their handset over the next few months.
The 27 million customers with the pair, which merged to form the Everything Everywhere group in 2009, are currently automatically connected to whichever of the two networks has the stronger signal where they are.
This means they stand a stronger chance of getting reception to make calls.
However, when customers are connected to whichever of the pair is not their host provider, they are unable to access the '3G' network which is required for fast internet speed (see the Orange/T-Mobile internet struggle MSE News story).
This has left many users frustrated by snail-like web speeds, making the downloading of large files or complicated internet pages a nightmare. When they are on their host network, they will get 3G.
From next week, Everything Everywhere will begin the 'big 3G switch on' which will eventually give all Orange and T-Mobile customers access to 3G internet speed regardless which network they are connected to.
Until all customers can get universal 3G, there is a way to bypass auto-connection to both networks (see the Orange/T-Mobile internet struggle MSE News story for details), though this means less chance of a strong signal to make calls.
Everything Everywhere cannot state exactly how long the full roll-out will take, only stating it will be complete "over the next few months".
Users will be notified by text when they are switched on.