Mobile phones are now heavily used for data communications such as SMS messages, browsing mobile web sites, and even streaming audio and video files. The main limiting factors are the size of the screen, lack of a keyboard, processing power and connection speed. Most cellphones, which supports data communications, can be used as wireless modems (via cable or bluetooth), to connect computer to internet. Such access method is slow and expensive, but it can be available in very remote areas.
With newer smartphones, screen resolution and processing power has become bigger and better. Some new phone CPUs run at over 400 MHz. Many complex programs are now available for the various smartphones, such as Symbian and Windows Mobile.
Connection speed is based on network support. Originally data transfers over GSM networks were possible only over CSD (circuit switched data), it has bandwidth of 9600 bit/s and usually is billed by connection time (from network point of view, it does not differ much from voice call). Later, there were introduced improved version of CSD - HSCSD (high speed CSD), it could use multiple time slots for downlink, improving speed. Maximum speed for HSCSD is ~42 kbit/s, it also is billed by time. Later was introduced GPRS (general packet radio service), which operates on completely different principle. It also can use multiple time slots for transfer, but it does not tie up radio resources, when not transferring data (as opposed to CSD and like). GPRS usually is prioritized under voice and CSD, so latencies are large and variable. Later, GPRS was upgraded to EDGE, which differs mainly by radio modulation, squeezing more data capacity in same radio bandwidth. GPRS and EDGE usually are billed by data traffic volume. Some phones also feature full Qwerty keyboards, such as the LG enV.
As of April 2006, several models, such as the Nokia 6680, support 3G communications. Such phones have access to the Web via a free download of the Opera web browser. Verizon Wireless models come with Internet Explorer pre-loaded onto the phone.
New features
There are also new means of digital communications, such as text messaging and e-mail. As of 2004, even basic phones can send and receive text messages which makes them vulnerable to attack by worms and viruses[citation needed]. Advanced phones capable of e-mail can be susceptible to viruses that can multiply by sending messages through a phone's address book[citation needed]. Of more important concern, a virus may allow unauthorized users to access a phone to find passwords or corporate data stored on the device. Moreover, they can be used to commandeer the phone to make calls or send messages at the owner's expense[citation needed]. Unlike computers that are restricted to only a few widespread operating systems, cellular phones use a variety of systems that require separate programs to be designed in order to disable each one. While reducing overall compatibility from an application design standpoint, this has the beneficial effect of making it harder to design a mass attack. However, the rise of cellular phone operating system programming platforms shared by many manufacturers such as Java, Microsoft operating systems, Linux, or Symbian OS, may in the future change this status quo.
Bluetooth is a wireless communication feature now found in many higher-end phones, and the virus Caribe hijacked this function, making Bluetooth phones infect other Bluetooth phones running the Symbian OS. In early November 2004, several web sites began offering a specific piece of software promising ringtones and screensavers for certain phones. Those who downloaded the software found that it turned each icon on the phone's screen into a skull-and-crossbones and disabled their phones, so they could no longer send or receive text messages or access contact lists or calendars. The virus has since been dubbed "Skulls" by security experts. The Commwarrior-A virus was identified in March 2005, and it attempts to replicate itself through MMS to others on the phone's contact list. Like Cabir, Commwarrior-A also tries to communicate via Bluetooth wireless connections with other devices, which can eventually lead to draining the battery. The virus requires user intervention for propagation however. Bluetooth telephones are also subject to bluejacking, which is the generally being transmission of messages from anonymous Bluetooth users. In 2004, rumors spread of using Bluetooth to arrange casual sex hookups; this activity, widely publicized in both print and online media as toothing, was revealed to be a hoax in 2005.
