iPhone 15/16 Series: Complete eSIM Setup Tutorial & iOS 18 Guide

The transition to eSIM-only devices has accelerated with the release of the iPhone 15 and 16 series. In major markets like the United States, the physical SIM tray is a thing of the past. For travelers, this shift is a blessing in disguise, offering unprecedented flexibility and ease of connection. Paired with the new connectivity features in iOS 18, managing your global data has never been simpler.

Why iPhone 15/16 is the Ultimate Travel Tool

The latest iPhone models support storing up to 8 or more eSIM profiles, with two active at any given time (Dual Active eSIM). This means you can keep your home number active for calls and texts while simultaneously using a local data eSIM for internet access. No more fumbling for a SIM ejector tool on a moving plane or risking the loss of your primary SIM card.

Step-by-Step eSIM Activation

Activating an eSIM on your iPhone is straightforward. Here are the three most common methods:

Method 1: QR Code Scan (Recommended)

This is the standard method for most travel eSIM providers like RoamHoliday.

1. Ensure your iPhone is connected to Wi-Fi.
2. Go to Settings > Cellular (or Mobile Data).
3. Tap Add eSIM.
4. Select Use QR Code.
5. Scan the QR code provided in your confirmation email.
6. Follow the prompts to label your new plan (e.g., "Japan Travel").

Method 2: Manual Entry

If you cannot scan a code (e.g., the code is on the same device), use manual entry.

1. In the QR code scanning screen, tap Enter Details Manually at the bottom.
2. Copy and paste the SM-DP+ Address and Activation Code from your email.

Method 3: Direct App Installation

Many carrier apps allow one-tap installation. Simply purchase your plan in the app and tap "Install eSIM" to automatically configure your settings.

Mastering Dual SIM on iOS 18

iOS 18 introduces refined controls for managing multiple lines. Here is how to configure your device for optimal travel performance:

Data Switching Settings

Go to Settings > Cellular > Cellular Data. Select your Travel eSIM as the source for data. Crucially, turn OFF "Allow Cellular Data Switching" to prevent your phone from accidentally using your home carrier's expensive roaming data if the travel signal is weak.

iMessage and FaceTime

You can continue using iMessage with your primary number. When prompted, select your Home line as the default for iMessage and FaceTime. Your travel eSIM will provide the data connection needed to send the messages without roaming fees.

Troubleshooting Common Issues

Even with the best technology, hiccups can happen. Here are quick fixes:

• "Unable to Activate eSIM": Ensure you have a stable Wi-Fi connection. VPNs can sometimes interfere with activation; try disabling yours temporarily.
• No Signal / SOS Only: Check that Data Roaming is turned ON for your Travel eSIM profile specifically. It is often off by default.
• Slow Speeds: Toggle Airplane Mode on and off to force the device to re-register with the nearest tower. If persistent, check your network selection settings and try selecting a carrier manually.