Panasonic JT-H300HT-E1 Operating Instructions Manual page 16

Insert/Remove a SIM Card
Place the SIM card on the tray.
4
Make sure the card is correctly directed.
After placing the SIM card on the tray, push back the tray until it clicks.
Note:
• Push back the tray surely to the end. Otherwise, the battery pack may not be inserted.
16
(JT-H300HT-E3)