Microsoft Lumia 640 LTE Single Sim - Manual (Page 5)

Insert the SIM and memory card
1. Slide the micro-SIM card into the SIM slot with the
metal contact area down.
2. If you have a memory card, slide the card into the
memory card slot.
It is recommended that you use a fast microSD card
from a well-known manufacturer.
Use only original micro-SIM cards. Use of
incompatible SIM cards, or use of SIM card adapters,
may damage the card or the device, and may
corrupt data stored on the card.