Why do Apple SMS messages have different color backgrounds?

The messages displayed in green belong to the messages of traditional operators, that is, they are generally charged according to the number of messages. There is no limit to the sending of this short message, and it can be used regardless of the mobile phone model.

The background color is blue SMS, which is a service provided by Apple for its own devices to send information through the network for free, that is, iMessage information, whether using wireless network or mobile network.

Of course, certain conditions are required when sending information with blue background. First, you must use Apple iPhone to open the iMessage function service in Settings-Information. In addition, the other party also uses Apple's mobile phone. After opening the iMessage service, they can send free messages to each other. It is worth mentioning that you can not only send free iMessage blue messages between iPhone, but also send messages between iPod Touch, iPad and Mac, as long as both parties enable iMessage service.