What's the difference between a SIM card and SD card?

Some of the listings on the Tophatter marketplace state that they require a SIM card to use all the features. Some of these same items may also require an SD, which may also be described as a TF card.

You may be wondering what all these abbreviations mean, and what you will actually need to operate the item. 

In basic terms:

  1. the SIM card comes from your cellular provider and is what provides your phone number to the device.
  2. the SD card can be purchased as an accessory, and it is what stores your external data such as pictures, songs, videos, applications, documents, etc.

SIM cards - cellular service

SIM stands for "subscriber identity module" and this is the small card that is issued by your cellular/mobile service provider which allows the device it is inserted into to operate on the cellular network and communicate with other devices on the network. 

This card is required for some items such as smart-bands and watches to be able to accept phone calls and text messages. Some applications such as the pedometer and alarms on these items will still work without a SIM card, but the device will not be fully functional, because it will not be able to tell you when you're receiving a call or message. 

SD & TF cards - memory

SD stands for "Secure Digital" after the association that sets the standards for memory cards. These types of cards use flash memory to expand the storage capacity of your device, upgrading the amount and size of data that your smart device will hold.

SD, TF, TransFlash, microSD, and other names you might see, are used to describe storage or memory cards. SD and TF cards can usually be used interchangeably, except in the case of GPS, Bluetooth and Near Field Communication devices. TF cards can't perform these non-memory jobs, so if your device uses these functions, you might need an SD card instead.

We recommend consulting the instructions for your specific device to be sure which card type and size is needed.