A SIM card (or “Subscriber Identity Module” card) is what connects your mobile device to a network. SIM cards are used in mobile devices like phones and tablets to provide an internet and mobile network connection without the use of Wi-Fi. Each activated phone uses a SIM, and most phones today are purchased through an expensive long-term contract with a mobile service provider. These devices come with SIM cards already in them. In fact, it can be difficult to purchase a top-of-the-line, brand new phone without a SIM card. However, when you do acquire a SIM-free phone or unlock a phone, you can buy cheaper and shorter-term SIM only contracts. In these deals, you provide your own phone and the network provider will give you a card to activate it.
There are many different kinds of SIM cards with different sizes and functions, and certain phones need specific types. Popular SIM card types include:
3G SIM cards are one of two types of specific SIMs that connect devices to that particular generation of mobile data. This SIM typically allows you surf the web at around 6 to 12Mbps.
4G SIM cards are another type of SIM that connects you to a specific generation of data. 4G speeds are vastly superior to the previous generation’s and can run upwards of 50Mbps.
The mini SIM card also called the standard SIM is the most commonly used SIM card.
Micro SIM cards are about half the size of a mini SIM and are used in new phones including the iPhone 4 and 4s.
Nano SIMs are the smallest version of the SIM cards. Only a few phone models employ the nano SIM like the Moto X and the iPhone 5.
International SIM cards identify your phone to your provider as capable of international roaming.
The right card for you will depend on your needs, including the device you own, which network you will be going with, the amount of minutes and data you require, and where you plan on using your phone. In order to make it easier to compare top plans, have a look on the deals page to compare everything and narrow down your choices.