Mitihoon – True is alerting the final group of customers who are still using 850 MHz SIMs and have not yet upgraded. We urge you to check your SIM now and switch to a new one before the August 3, 2025 deadline to ensure maximum performance, especially for international roaming services. While your current SIM will continue to work for domestic usage, upgrading will ensure smoother, full-performance connectivity both in Thailand and abroad.
Instantly receive 3GB of free domestic data and 50 minutes of free calls for 7 days upon successful SIM replacement. Plus, get an additional 4GB of free roaming data when you purchase the GO Travel package for international use from August 1 to September 15, 2025.
Easy Check: Is Your SIM 850 MHz?
True customers can easily check their SIM status using two simple methods:
- For the SIM in your current phone: Dial *850# and press call
• For a SIM in another phone or device: Dial *850*[10-digit phone number]# and press call (e.g., *850*08xxxxxxxx#)
You will receive an SMS response informing you of the status. If the message states something like “Your SIM card must be changed urgently…”, you are in the group that needs to replace your SIM.
Who Needs to Change Their SIM?
Customers using True 850 MHz SIMs—which may still be working normally—should be aware that the 850 MHz spectrum contract with NT will expire on August 3, 2025. Replacing your SIM ensures uninterrupted service, especially if you plan to travel abroad. Without changing your SIM, you will not be able to use roaming services after August 3, 2025.
This also applies to customers using True SIMs in communication or IoT devices, such as SIMs in security cameras, as well as those using eSIMs or multi-SIMs. Some of these cases may also require SIM replacement.
Where and How to Change to a New SIM
True offers convenient, free SIM replacement through three main channels:
- At any True Shop
Bring your national ID card (or passport for foreign customers) and your old SIM card to any True Shop, dtac Shop, or TrueSphere branch. - Call 1242
Contact the True Call Center to request home delivery of a new SIM with step-by-step replacement guidance. - eSIM Customers
Conveniently upgrade through the True iService app using the “Change/Upgrade eSIM” menu.
What Documents Do You Need?
- Individual customers: National ID card or passport, and old SIM card
- Corporate customers: National ID card or passport, old SIM card, and employee ID card or proof of employment
After SIM replacement, your package and benefits, including your phone number, will remain exactly the same.
For the best user experience and uninterrupted service, especially for international roaming, don’t wait. Check and change your SIM today, before August 3, 2025.
For more information, contact the True Call Center at 1242. If you are abroad, call +66 9999 81242.
