Technical Setup

Complete Dual SIM Setup Guide: Keep WhatsApp & Receive Bank 2FA SMS Overseas

Devon Chen · Lead Systems Engineer
August 25, 2026
6 min read

# Complete Dual SIM Setup Guide for Global Travelers

Many travelers worry that installing a travel eSIM will overwrite their WhatsApp number, disconnect their iMessage, or block two-factor authentication (2FA) SMS from banks and credit cards.

Good news: **you do not lose any of your existing accounts or phone number functions.**

How iOS Configures Dual SIM

1. Open **Settings > Cellular**. 2. Tap your primary physical SIM and label it **"Primary"**. 3. Tap your newly scanned AeroSIM profile and label it **"Travel"** or **"AeroSIM"**. 4. Set **Default Voice Line** to **"Primary"**. This ensures phone calls and standard SMS route through your normal number. 5. Set **Cellular Data** to **"Travel"**. 6. Switch **"Allow Cellular Data Switching"** to **OFF**.

WhatsApp Configuration

When you first open WhatsApp after switching data to your travel eSIM, WhatsApp may display a prompt asking: *"Your phone number has changed. Would you like to update it?"*

**Always select "Keep Existing Number" (or "No").** WhatsApp will continue using your home phone number for all chats, groups, voice calls, and media over the high-speed AeroSIM data network.