A Subscriber Identity Module (SIM) is an integrated interconnectivity circuit with a microchip that stores information of a user while linking subscribers to others using the Global System of Mobile communication channels. A smartphone, on the other hand, is a complex mobile and technological device used in sharing information, both verbal and short message services. With such features, the smartphone needs a good SIM card to complement this usage.

Types of SIM Cards

1. Standard SIM – this is the oldest and the largest of the three SIM cards. It was circulated pre 2010 and was 25 by 15 by 0.75millimetres. The type of phones then, which were mostly feature phones, could only fit in the SIM. However, with the advent of technology and reduction in the size of phones, it is rare to see these SIM cards in circulation.

2. Micro SIM – it is a smaller version of the standard SIM in terms of width and length, although the height remains the same. They were trimmed to make smartphones slimmer and lighter. They were released post-2010 and measured 15 by 12 millimetres. They are still operational to date based on the type of handset used.

3. Nano SIM – this is the newer generation SIM, introduced in 2012. It measures 12 by 8.8 millimetres. The height is 0.67 millimetres, which is 0.09 smaller than the first and second generation SIMs.

4. The fourth type of SIM is a combination of the three: a Nano SIM housed within a micro SIM, encompassed in a standard SIM. The three can be separated by breaking the plastic surrounding each SIM. Each SIM is measured to scale and is designed to be used in all the type of gadgets available. They are mostly found in the Pay-As-You-Go stores.
All the three types of SIM cards work exactly the same. There is no technological improvement on the microchip, save for the size of plastic surrounding each type.

Type of SIM to Use
The type of SIM to use is prescribed by the smartphone manufacturer. It is usually written on the usage or instruction manual. There are also some configured phone manufacturers who prescribe the type of SIM they use, written on the cover box. If not provided in the user manual, an online search on the manufacturer’s website or any telecommunication products website will provide the information. In case a user needs to know which type of SIM card he or she has, they are identified by the size of the microchip vis a vis the plastic surrounding it. The Nano is the smallest, covering only the size of the chip, followed by the Micro, while the standard is the largest.
In case a user is changing the handset and the previous smartphone used a Nano SIM, while the new smartphone uses a Micro SIM, there is an inexpensive modifier in Phone shops, telecommunication service provider’s retail outlets or online merchants like Amazon. They provide an extra layer to fill up the space left to the preferred size of the SIM. If the new phone uses Nano while the old one used Micro SIM, the safe way to do it is swapping the SIM to get the right size. The information would remain the same. Otherwise, the user can trim it manually, which pose the risk of damaging the microchip if care is not taken.

Phone Brands with their Preferred SIM
The only Apple smartphone that uses the standard SIM is the iPhone 3GS. The rest (The 4, 5, 6, 7, 8 SE and X series) uses the nano-SIM except iPhone 4 and iPhone 4S which uses the Micro SIM.
All the Google smartphones use Nano Sim while no MicrosoftNokia or Motorola phone uses standard SIM. Microsoft Lumia 550, 650, 950 and 950L use the Nano SIM. The rest use micro SIM.
Samsung has the largest number of phones that use the Standard SIM; Nexus S and selected galaxy brands (Ace, Ace2, Fame, Music, Note, S, SI, SIII Mini, X Cover III, Y, Young and Young 2). Motorola has the largest number of phones using the Nano SIM compared to other brands while Nokia has the largest number of smartphones using the Micro SIM.
Huawei brands that use Standard SIM are the Ascend G300, G330, G510, P1 and Y3. The rest either use Nano or Micro SIM. As for LG, only L70 and L5 II use standard SIM. The only Sony brands that use standard SIM are Xperia E, E1, J, and miro. The rest use either micro or Nano SIM.
Nonetheless, all the smartphone manufacturers have either Nano or Micro SIMs.