Sony SGPT21 - Manual (Page 29)

Notes on the SIM Card
Make sure the power of your tablet device is turned off before inserting or removing the SIM card.
Do not press the SIM card more than necessary when inserting or removing a SIM card.
If you remove the SIM card right after using your tablet device, the SIM card may be warm. This is normal
and does not indicate a malfunction.
Avoid exposing the SIM card to very cold, hot, humid places.
Do not touch the contacts or terminals with your fingers or metal objects. If dirty, wipe the card with a soft
cloth and keep it clean.
Do not drop, press, or bend the SIM card.
Do not insert the SIM card with labels or stickers in place.