A mobile phone, cell phone or hand phone, also sometimes shortened to just mobile, hand phone or just mobile, phone is a mobile telephone which can make and receive telephone calls over an unlicensed radio frequency signal when the user is within a certain telephone service zone. In other words, all calls made within a certain area code are allocated to a certain mobile or hand unit. The zones could be city, state, country or just a certain radius around your location.

The invention of the mobile phone was originally a single unit device used for one function, such as receiving or making telephone calls. However, with the development of the cellular operating systems and the addition of features such as text messaging, Internet browsing, and the ability to send and receive email attachments, the humble mobile has evolved into a multifunctional communication device. Today, mobile devices are often used for data applications, entertainment purposes and even as an ordinary telephone. With the continued advancement of the cellular technology and the addition of several new applications, the mobile telephone has become a multi-tasking device used for tasks ranging from telematics to Internet use.

One of the most popular applications that can be found on the mobile device is the application called Skype. This type of application enables users to use their wireless connection to chat with other Skype users within a specified area or around the globe. When using Skype, one can use the speaker capability to talk through the device or through a text messenger or by typing in a chat window like a normal text based messaging program would. A major advantage of this application is that users can actually speak with someone located in a completely different part of the world! Many people who use Skype have discovered that they can save money by purchasing roaming phone service, since they no longer need a cell phone or land line telephone to make telephone calls abroad.