The mobile phone giant, formerly known as BT Cellnet, is set to argue that 3, owned by Hutchison Whampoa, has infringed on its trademarks by using bubble images for a campaign for its pay-as-you-go service Three Pay that involved broadcast and print media in August.
MMO2 has used the oxygen bubbles for its advertising since 2001. According to media reports, the firm will also look for damages.
A spokesman for MmO2 said: "We believe that it is particularly important to protect what we see as synonymous with our brand." He added that the matter is due before the High Court this Friday and declined to comment on the amount of damages being sought.
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