Its not so much what they put on their as to what they take off and disable. Vodafone Disabled the ability to set MP3 files as ringtones on the Nokia 6630. Vodafone denied this but coincidently their own ringtones sold on their site were MP4 (which worked fine). Every other variant allowed MP3s fine. They have also been known to disable Skype and other features that riveled their own.