Users can protect themselves by carefully reading any message that asks them to download an application, or safer still, setting their phone to only allow downloads via the Android Marketplace.

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The photos alone are worth the download, but the message in the text is precisely what many makers are about.

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Mr Mazkouri described himself as a technophobe who had trouble sending a text message, so was "dumbfounded" by the download of such a huge chunk of data.

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It's also, of course, deeply integrated into Windows 8 itself, even taking advantage of a new networking APIs to detect if you're on a metered network and only download the first first 20KB of each message body if that's the case.

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It will also be available as a download for phones on other networks and via a text message link.

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The first sign of attack is a message that appears to come from a contact, offering you a file to download.

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Chorus.im does, and claims it has a new idea: people should be able to mobile message one-to-one, or in groups, without having to download and register with any app at all.

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Users download the free application off the Web, but instead of typing a text message, they use a headset, telephone or microphone and speakers to make a high-quality, two-way voice call to anyone else running the application.

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Apple tells its customers they must not download an app if they fall below the stated age limit - but users can click away the warning message.

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