BT has announced it will rebrand its wireless operations under the O2 name.

UK telco BT on Monday announced that its mobile business, which had been called BT Wireless, will now be called mmO2 plc. It will adopt the O2 brand for all consumer operations, renaming brands such as BT Cellnet and Viag Interkom to O2 from spring 2002. When the unit is spin off from BT later this year, it will be listed as mmO2 plc.

Also on Monday, Deutsche Telekom announced that it would abandon the One2One name for its UK mobile operation, despite the estimated $150 million invested in developing the brand. It will be renamed T-Mobile to fit in with DT’s other mobile operations.

It’s easy to see why building global brands is important to mobile operators. Having invested billions of dollars in 3G licenses and infrastructure, they are desperate to see a return on investment, and so will certainly spend hugely on marketing campaigns for the new services. In all industries, as the media becomes increasingly pan-regional, using the same brand internationally allows companies to market their services more effectively – just consider Unilever’s plan to ditch local names and focus on a few globally strong brands. Similarly in the mobile arena, Vodafone’s sponsorship of Manchester United builds brand awareness throughout the world.

The ultimate example of a successful mobile brand is Orange. France Telecom has also abandoned its local brands, unifying its services under the Orange name. Orange is seen as unstuffy, innovative and consumer-focused, with the brand acting as a clear draw to customers. Clearly it’s in France Telecom’s interests to use the name as widely as possible.

However, Vodafone, T-Mobile and O2 certainly aren’t yet close to Orange. The first two are still seen as mobile phone companies, rather than ‘lifestyle’ brands. And O2 is currently just a made-up name. Unifying brand names globally is an important first step as the mobile industry becomes a mature consumer market. But the real branding challenge will be to make consumers identify with the new names.