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“SIM card activation failed” on a Xiaomi phone can refer to activation of a Xiaomi account service, rather than the carrier refusing to register the SIM. First check whether calls, ordinary SMS and mobile data work. A “no SIM” or “no service” message needs carrier and hardware checks instead.
Check SMS before changing network settings
- Restart the phone and confirm that the SIM is detected.
- Send a normal SMS to a known contact. Xiaomi says activation can fail when regular SMS cannot be sent.
- Ask your carrier about balance, outgoing-message restrictions and any activation-message charges. On dual-SIM phones, confirm which SIM is being used.
- Check that the Xiaomi account’s phone number and country code match the number you intend to activate.
An APN is primarily a mobile-data setting. Changing it is not a universal fix for a failed activation SMS. Avoid copying unrelated carriers’ APN values.
Retry the Xiaomi service
Use the activation notification to retry. Xiaomi’s current troubleshooting instructions describe a manual-number-entry option that may appear after several retries, including for some ported or virtual numbers. If it does not appear or does not work, repeatedly retrying is not a useful next step.
Account and service menus differ between MIUI, HyperOS versions and regions. Review any requested SMS permission through system settings. If you sign out and back in, first ensure you know the account credentials and understand any sync or device-finding prompt.
Identify SIM versus phone problems
When practical, compare another working SIM in the phone, or test your SIM in another compatible phone. If only your SIM fails, contact the carrier. If the problem follows the phone, contact Xiaomi support with the model, software version, exact error and test results.
Do not start with a factory reset or a language-change “trick.” Protect your files before any reset requested by support; our backup guide explains restore checks. Share diagnostic logs only through an appropriate official support channel, because they can include device and account details.