How does iphone5 mark a read SMS as unread?

Just go to Settings SMS and turn off sending the read receipt.

1, short message service (SMS) is a part of unified communication service planning.

2. Text or digital information directly sent or received by users through mobile phones or other telecommunication terminals.

3. The number of characters that users can send and receive short messages at a time is 160 English, numbers or 70 Chinese characters.

4. Short message is a kind of telecommunication service accompanying digital mobile communication system, which passes through the signaling channel and signaling network of mobile communication system.

5. Sending text or digital short messages is a non-real-time and non-voice data communication service.