How to Use Dual SIM to Compare Two Carriers at Once

Thanks to eSIM technology, most modern smartphones allow you to run two active plans simultaneously.

This setup is the ultimate way to test a new carrier. You can keep your primary number for talk and text while routing all your cellular data through a free trial.

It allows for a side-by-side, real-time comparison without any downtime or risk of missing an important call.

Here is how to set up your phone for a dual-carrier showdown.

Step 1: Check Your Hardware

Before you start a trial, make sure your phone can handle two lines at once. Most flagship phones released recently are "Dual SIM" capable, usually through a combination of one physical SIM slot and one digital eSIM.

• iPhone: iPhone XS, XR, and all newer models (including the iPhone 15 and 16 series, which are eSIM-only in the US).
• Android: Google Pixel 3 and newer, and Samsung Galaxy S20 and newer.
• Carrier Status: Your phone must be unlocked. If you are still making payments on your phone to your current carrier, they may have the eSIM slot locked, which prevents adding a second line.

Step 2: Start Your Trial via eSIM

Once you've chosen a carrier to test (like T-Mobile, Verizon, or AT&T), download their official app. During the sign-up process, choose the eSIM option.

Your phone will walk you through a few system prompts to "Add Cellular Plan." You will be asked to label your lines. Labeling your original line as "Primary" and the trial line as "Trial" or "Secondary" avoids confusion later.

Step 3: Route Your Data

This is the most important step for an accurate comparison. You want your phone to use the new carrier for all the "heavy lifting" (web browsing, streaming, and apps) while keeping your phone number active on your old network.

On iPhone:

1. Go to Settings > Cellular.
2. Tap Cellular Data and select your Trial line.
3. Turn off "Allow Cellular Data Switching." This ensures your phone stays on the trial network even if the signal is weak, allowing you to find the new carrier's true dead zones.

On Android:

1. Go to Settings > Network & Internet > SIMs.
2. Select your Trial SIM.
3. Toggle Mobile Data to ON for the trial line.
4. Switch your primary SIM data to OFF (but keep the SIM active for calls and texts).

Step 4: The Side-by-Side Test

With both lines active, your phone's status bar will now show two signal meters. This is your first visual clue into the local coverage differences.

The Speed Test. Download a speed test app. Run a test on your Trial line, then go back into settings, switch the Cellular Data back to your Primary line, and run the test again in the same spot.

The Signal Check. Watch the signal bars as you move into difficult areas like elevators, grocery stores, or your home's basement. You will often see one carrier hold onto a signal while the other drops to "No Service."

Step 5: Battery Life

Running two active lines (Dual SIM Dual Standby) does use slightly more battery than a single line. If you notice your phone dying faster than usual during the 30-day trial, this is normal. Your phone is pinging two different sets of towers. Once the trial is over and you remove the second eSIM, your battery life will return to standard performance.

Prefer a Video Walkthrough?

This video provides a complete visual walkthrough for setting up and managing two separate carriers on an iPhone, which is helpful for seeing exactly where the settings are located.

This video provides a complete visual walkthrough for setting up and managing two separate carriers on an iPhone, which is helpful for seeing exactly where the settings are located.