Joke Collection Website - Public benefit messages - On the two iPhone 5s, text messages sent were blue, and you could see delivery and read. It's still blue now, but only one has been delivered.

On the two iPhone 5s, text messages sent were blue, and you could see delivery and read. It's still blue now, but only one has been delivered.

It’s iMessage. Go to Settings-Message-Open iMessage, you need to log in with apple

ID. After logging in, the option "Send read receipt" will be turned on, and the sender will be notified after reading the message.

The mobile phone number of the person you want to send to also has iMessage enabled.

If you want to know whether the call is open, select this contact in the input contact field, and iMessage will be displayed after a while.