SIM Form Factor : UICC, eUICC, 2FF, 3FF, MFF2 explanation

• SIM Technology choice
  • UICC (Universal Integrated Circuit Card)
  • eUICC (Embedded Universal Integrated Circuit Card)
  • The difference between UICC and eUICC is the downloadability of the profile after installation to the board. With eUICC, we can remotely switch operator profiles without touching the device.

• SIM Card Form Factor (2FF, 3FF, 4FF)
  • It depends on the card sizes. 1FF is no longer used, from 2FF~4FF is in use for cellular connectivity.
• Chip SIM Form Factor (MFF2)
  • This is also known as Chip SIM, which means that it can be soldered directly onto the PCB board. It has some advantages.
    
    1. Saving board space
    2. SIM can be sealed and protected from corrosion
    3. Good choice for devices that are constantly moved and in danger of the drop
    But it also have disadvantages.
    1. It is hard to install this with UICC
    If UICC is installed with MFF2, the device would be locked into a single provider during the lifecycle.