Xiaomi
Send an SMS Text Message auf Xiaomi
MIUI does not separate SMS and MMS into different apps. Every text, whether plain or with an attachment, appears in the same conversation thread inside the Messages app.
To send a plain SMS, open the app and tap Tap on Messages. From there select Tap on Start chat to begin a new conversation.
Next, use Enter a Phone numberor choose a Contact to pick the recipient. Type your text in the field described by Type a Message, then confirm with Tap on Send.
The message goes out as SMS as long as it only contains text. The moment you attach a photo, video, or voice note, MIUI converts the same conversation entry into an MMS and it may use mobile data instead of your SMS allowance.
Conversations stay grouped by contact, so sent and received texts in one thread can mix SMS and MMS without a visible label. If a message fails to send, check your signal and carrier settings before assuming the Messages app itself is broken.