In our era, things that we normally employ for luxury are now regarded as essentials as time went by. An example of this is a mobile phone. With the might of technology blissfully wrapping us in its splendor, we succumb to its vastness and promise of convenience. Desires of technological dependencies and comfort are what moves us to purchase devices such as mobile phones and with the endless innovations it partakes the more individuals are inclined to get them. Nearly three-fourths of the world's population happens to hold a mobile phone and more than half even holds more than one. Mobile phones are gaining popularity by the minute among adolescents and business users alike, but with all this hoopla, we have to likewise remember that the mobile phone is unusable without a mobile carrier and a SIM card. If the battery is the life of the mobile telephone, the SIM Card is the heart that makes blood circulate to the whole device to operate. The SIM or Subscriber Identity Module ordinarily bears many valuable data. Just like your normal identity card, the SIM card bears the contact number with which your mobile phone is fixed with. Talking about contacts, a Subscriber Identity Module can store up to 250 contacts or more depending on your mobile provider. In addition, shifting to a new SIM card permits you to possess a new mobile carrier with some other mobile number which you may utilize on your sim free mobile device. The Sim or Subscriber Identity Module also holds an IMSI or in secular's terms, a service subscriber key. The latter is used by mobile phone carriers and operators to distinguish a specific subscriber what is more; the IMSI comprises of 15 numbers. The mobile country code is depicted by the 1st 3 digits while the mobile network/carrier code is depicted by 2 digits and the leftover 10 numbers is the genuine mobile number itself. Flexibility is also what Subscriber Identity Module cards provide since they can be used with any unlocked mobile phone. This is extremely useful specially when travelling and you ran out of battery. If you have an extra mobile phone, then all you require to do is just alternate the SIM card. Once you've inserted the SIM card into an alternate phone you can make and receive messages and calls just like it was your own phone. Again, due to recent advancements in technology, some mobile phones offer a dual-SIM functionality. Don't let that spare mobile phone lay to waste just lying around the house, just pop-in a new SIM card and get ready to go.