INQ and HTC are hard at it releasing "Facebook phones" but Twitter will not be joining the fight with their own "Twitter-branded" phone. Twitter CEO Dick Costolo said at the Mobile World Congress that although 40-percent of all tweets come from mobile phones, Twitter does not want it's own handset.

Costolo said he'd like to see deeper Twitter integration on mobiles, but at somewhat of a limit: "I believe there is a need [to better integrate] Twitter in existing platforms for phones, but not for a Twitter-branded smartphone," he told an audience of people more used to seeing operators, handset makers and network vendors than they are social media juggernauts keynoting the event.

As for the definition of his "deeper integration", Costolo pointed out that on an Android-based phone a person can take a picture and automatically send it in a tweet to their followers. He said there needs to be more of that removal of complexity. "What I would like are more single sign-on experiences, more apps that can tweet without having to go to another app."