Why are there two kinds of SMS messages on iPhone: blue and green?

There are two kinds of short messages on iPhone: blue and green.

There is indeed a difference between two color messages;

The short message displayed in green indicates the traditional short message sent at present, that is, the short message sent by the operator needs to be paid;

If it is a blue message, it means that it is sent through Apple's iMessage service, that is, the information sent through the network is free;

Green SMS

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 model of the mobile phone. This kind of short message is used by traditional operators, namely mobile, telecom and Unicom. In addition, you can also see a prompt with the words "SMS/MMS" in the SMS text input box.

Blue SMS

Blue SMS is a service provided by Apple for iOS devices. Whether using wireless network or mobile network, you can send information through the network for free, that is, iMessage information. This kind of short message can only be used when both parties use iPhone, and both parties have opened iMessage service and have network connection.