It depends on the model. Some two-slot phones have no eSIM chip at all, while others have both but limit how many lines can be active together. The most reliable check is to open the network settings on the handset itself and look for a control that adds a digital line or scans a QR code. If there is none, that unit does not support it, whatever a specification page says.

Usually not; the phone remembers the settings for that line and resumes. The two things worth re-checking after reinserting are which line is the default for data and whether roaming data is off. When a line disappears and comes back, some systems reassign the default data line on their own, which can quietly put you back on the line you meant to avoid.

A paperclip with the end straightened is the best stand-in; a straight-post earring will also do. Avoid anything that splays or snaps, such as a toothpick that could break off inside the hole. If you have nothing at all, phone repair shops and many hotel front desks can lend you a pin. Do not press hard enough to damage the tray.

The card format does not set the speed. Both hold the same kind of identity and use the same networks. What you actually get depends on the network you are attached to, the terms of the plan, the priority the network gives that group of users, and how busy the area is at that moment. If two SIMs behave differently, look at the plan and the network rather than at the plastic.

Always in the carry-on. If checked luggage does not arrive with you, neither does the card, and the moment you most need it is often the moment your bag is missing. The right place is a small compartment that closes properly and that you do not open repeatedly through the day.

Message us on LINE at https://lin.ee/skDPoNx (@esimonline) or email esimonline.asia@gmail.com. Telling us the handset model, the OS version, the country you are in, and exactly what the screen says lets us answer precisely and quickly. Those two channels are the only ones we operate; there is no telephone line.