Mobile Phone Parts, SIM cards and Mobile Phone unlocking
Mobile Phone - also known as a Cell Phone
A mobile phone or mobile (also called cellphone and handphone, as well as cell phone, wireless phone, cellular phone, cellular device, cell, cellular telephone, mobile telephone or cell telephone) is a long-range, electronic device used for mobile telecommunications (mobile telephony, text messaging or data transmission) over a cellular network of specialized base stations known as cell sites.
Most current mobile phones connect to a cellular network consisting of switching points and base stations (cell sites) owned by a mobile network operator (the exception is satellite phones, which are mobile but not cellular). In addition to the standard voice function, current mobile phones may support many additional services, and accessories, such as SMS for text messaging, email, packet switching for access to the Internet, gaming, Bluetooth, infrared, camera with video recorder and MMS for sending and receiving photos and video, MP3 player, radio and GPS.
As opposed to a radio telephone, a mobile phone offers full duplex communication, automatised calling to and paging from a public switched telephone network (PSTN), and handoff (American English)/handover (British/European English) during a phone call when the user moves from one cell (base station coverage area) to another. A mobile phone offers wide area service, and should not be confused with a cordless telephone, which also is a wireless phone, but only offer telephony service within a limited range, e.g. within a home or an office, through a fixed line and a base station owned by the subscriber.
The International Telecommunication Union estimated that mobile cellular subscriptions worldwide would reach approximately 4.1 billion by the end of 2008. Mobile phones have gained increased importance in the sector of Information and communication technologies for development in the 2000s and have effectively started to reach the bottom of the economic pyramid.
SIM Cards
A subscriber identity module (SIM) on a removable SIM card securely stores the service-subscriber key (IMSI) used to identify a subscriber on mobile telephony devices (such as computers and mobile phones). The SIM card allows users to change phones by simply removing the SIM card from one mobile phone and inserting it into another mobile phone or broadband telephony device.
A SIM card contains its unique serial number, international unique number of the mobile user (IMSI), security authentication and ciphering information, temporary information related to the local network (also temporary local id that has been issued to the user), a list of the services the user has access to and two passwords (PIN for usual use and PUK for unlocking).
SIM cards are available in two standard sizes. The first is the size of a credit card (85.60 mm × 53.98 mm x 0.76 mm). The newer, more popular miniature version has a width of 25 mm, a length of 15 mm, and a thickness of 0.76 mm. However, most SIM cards are still supplied as a full-sized card with the smaller card held in place by a few plastic links and can be easily broken off to be used in a phone that uses the smaller SIM.
The first SIM card was made in 1991, with Munich smart card maker Giesecke & Devrient selling the first 300 SIM cards to Finnish wireless network operator Elisa Oyj (formerly Radiolinja).
Unlocking a Mobile Phone
A SIM lock, simlock, network lock or subsidy lock is a capability built into GSM phones by mobile phone manufacturers. Network providers use this capability to restrict the use of these phones to specific countries and network providers. Currently, phones can be locked to accept only SIM cards from one or more of the following:
Countries (the phone will work in one country, but not another)
Network/Service providers (e.g., AT&T Mobility, T-Mobile, Vodafone, etc.)
SIM types (i.e., only specific SIM cards can be used with the phone).
In most countries, most mobile phones are shipped with country and/or network provider locks. In addition, these locked phones tend to have firmware installed on them which is specific to the network provider. For example, if you have a Vodafone or Telstra branded phone in Australia, it displays the relevant logo and may only support features provided by that network (e.g., Vodafone Live!). This firmware is installed by the service provider and is separate from the locking mechanism.
Most mobile phones can be unlocked to work with any GSM, such as O2 or Orange (in the UK), but the phone may still display the original branding and may not support features of the new carrier. Most phones can be unbranded by uploading a different firmware version, a procedure recommended for advanced users only.