Finland's Nokia is set to unveil three new models next week.
The world's largest mobile phone maker will show the "clam-shell" model 7200, the 6230 camera phone and the 6820 with keyboard at its Mobile Internet Conference in Nice, France, next Tuesday, the sources said.
The Finnish company declined to comment. Until now, Nokia has been reluctant to stamp an operator's brand on its phones, but the new models feature places for a logo of a mobile telecoms operator. Consumers would also be able to access carrier-specific services with special buttons.
Other phone manufacturers, such as Motorola, have no qualms about co-branding and this has added the pressure on Nokia to follow suit or risk losing business. Co-branding and special buttons have helped Japan's Sharp become the most popular phone maker for Vodafone's Live! service.
"A more relaxed attitude towards operator branding should help Nokia maintain its share as we suspect that operator branded phones are on the rise," said analyst Mr Richard Windsor at Nomura in London, who had obtained pictures of the new phones.
In Europe, Vodafone Live!, T-Mobile's T-zones and Orange's signature phones show that operators want models tailored to their network. In Japan and the United States this was already a trend.
An industry source pointed out that the new clam-shell model was the company's first response to a growing number of fold-away models which are popular in Asia and the US.