Mobile phone networks are encouraging smartphone users to take advantage of WiFi hotspots, it has been claimed.
Imran Choudhary, client manager at Kantar Worldpanel Comtech, explained "unlimited data tariffs are few and far between" because so many people are now accessing the internet on their phones.
Although unlimited data was the norm when the iPhone first came out on O2, this is no longer the case.
As a result, Mr Choudhary said networks are promoting the use of WiFi, with many individuals becoming more "savvy" and signing up to free hotspots.
Vodafone, Orange and O2 are all advertising BT Openzone as a way to divert data-heavy traffic away from their own networks.
"But that's still emerging and there's a lot of work to be done," the expert added.
In January, O2 announced it will be working with Westminster City Council and the Royal Borough of Kensington & Chelsea to establish the largest free wireless hub in Europe.