What happens if you breach mobile data 'fair usage'?

Vodafone has never charged or disconnected a customer for going over their mobile data usage limit.

That's according to John Lillistone, Vodafone's head of enterprise data, who explained the operator's new "3G Broadband", or HSDPA, offering to journalists and analysts on Thursday.

According to the fine print on Vodafone Web site, its data price plans are "subject to Vodafone's fair usage policy. This means that a customer's UK usage must not exceed 1GB per user account in a month" — even when the package offers supposedly "unlimited" data.

The terms and conditions continue: "We don't expect customers to go over this limit, however if a customer's usage is in excess of this, we may ask them to moderate their usage. If a customer then fails to do so, we reserve the right to move them to another Vodafone Data price plan or to charge for all excess usage. Long-term or persistent usage in excess of the limit may also result in suspension or termination of the service."

However, Lillistone said on Thursday that "to date, we have not disconnected or charged anyone under the fair usage policy", thus raising the question of what the policy is for.

A spokesperson for Vodafone said on Friday that the limit was a "deterrent for some people who may misuse the network", although the vast majority of its customers would never do so.

"If someone is misusing the network and permanently downloading large amounts of data, it's going to impinge on other users who are using the same cell," she told ZDNet UK.

"We ring them up, find out what they're doing, make sure they're using the right equipment in the right way — then we set them up with a bespoke tariff. We don't want to cut anyone off, we just want to make sure people are on the right tariff."

The spokesperson gave one example of a corporate customer who now has a 20Gb data limit with Vodafone, although she said the company tended to play down such tailored options in its marketing.

Ovum analyst John Delaney said on Thursday that a one gigabyte limit was in any case "quite low", and would discourage people from using the value-added services, such as streaming video, that Vodafone is trying to promote through 3G Broadband.

Vodafone's spokesperson conceded that, with the introduction of the new high-speed service, the company would "be looking at usage and see if the fair usage limit is the right one". In Germany, Vodafone offers customers a limit of 5GB a month.

O2 has similar terms and conditions to Vodafone UK for its data service, stating: "Fair usage policy applies, and average monthly usage is expected to be below 1024MB. O2 reserves the right to apply extra charges or to withdraw the Data Max 1024 service from any individual at any time in the case of suspected overuse or abuse of the service."

An O2 spokesperson told ZDNet UK that the operator had never exercised its right to terminate, saying: "We haven't yet seen the need to take action against a customer who may have exceeded their data usage limit." He said the "vast majority" of O2's data customers never exceeded the limit.

As for the other operators, Orange simply carries on charging by the megabyte once the limit is crossed, while 3 suspends data use until the next billing cycle.

T-Mobile, which has a larger limit of 2GB, threatens those who go over with nothing more than the possibility of "reduced speed of transmission".