Overview

This is a real case reported by a customer who regularly uses NeoKOSIM’s Vietnam eSIM during visits to Vietnam.
After arriving in Vietnam, the customer was able to use mobile data, receive SMS messages, make voice calls, and send messages through iMessage without any problems. However, regular SMS messages could not be sent.
In most cases, this issue is caused by iPhone message settings, iOS software issues, or temporary network registration problems.

Step-by-Step Troubleshooting

* Please follow the steps below in order.

* Step 1: Check Your iOS Version
– Go to Settings > General > Software Update
– Install any available updates
– Example: iOS 18.5 or later
– Make sure your iPhone is running the latest version of iOS.

* Step 2: Verify Message Settings
– Go to Settings > Messages
– Confirm that the following options are turned ON:
– iMessage / Send as SMS / MMS Messaging
* Note:
– Check that the required messaging options are enabled.
– iMessage uses mobile data or Wi-Fi and is different from standard SMS messages.

* Step 3: Reset Network Settings (Most Effective Solution)
– If the problem continues, reset your network settings.
– Go to Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings
– This step resolves most SMS sending issues by refreshing the network configuration and carrier settings

Additional Tip

– You will need to reconnect to Wi-Fi networks and re-enter saved Wi-Fi passwords after the reset.
– Restart your iPhone after completing the network reset.
– If the issue persists, please contact our support team for further assistance.
– We recommend testing your eSIM settings before your trip whenever possible.

*We hope this guide helps you resolve SMS sending issues quickly and enjoy a smooth travel experience in Vietnam.