Apple SMS has been sent for reading.

This means that only when both parties send messages with pictures can "Sent" be displayed first, and then "Read" be displayed.

Usually, if the message is sent successfully, "Sent" will be displayed, and "Read" will be displayed only when the other party sees the message content.

IMessage is an instant messaging software launched by Apple, which can send short messages, videos and so on. , high security. Different from the SMS/MMS service of operators, users only need to support data through WiFi or cellular data network to complete knowledge exchange.

Extended data:

With IMessage, you can send and receive information, as well as photos, videos, location information and contact information using iPad, iPhone, iPodTouch or Mac users running MountainLion.

If you have more than one Apple device, IMessage can have a continuous conversation on all devices.

Text messages, photos and videos can be sent to other mobile phones through the mobile phone network. Even Siri can help send text messages by saying "Tell Xiao Li I'm on my way", and then write to you and send text messages.

References:

Apple official website-About iMessage information and SMS/MMS