X-ray of an iPhone 4, showing the internal structure. The iPhone 4 mobile phone was introduced on 24 June 2010. It is a 'smart phone', having the ability to run various applications (known as 'apps') on its own operating system as well as take photos and video, send text messages and email and make video and voice calls. The phone's antenna was incorporated into the metal strip along the edge of the device - this led to early problems with signal strength dropping, which the manufacturer cured by supplying a thin rubber and plastic 'bumper' edging. Interface with the phone's many systems is through a glass touch-sensitive screen. It also has accelerometers, a gyroscope and a compass. The design of the phone, the name 'iPhone' and the Apple logo are registered trademarks of Apple, Inc.