Why do you also send text messages to each other's iphone, some green and some blue?

The green one is normal SMS, and the operator will charge SMS fee. The blue one is iMessage, which can only be used between iPhone and costs nothing. The premise is that the mobile phone turns on iMessage and the network, because iMessage uses traffic.

The iMessage service can only be used between iOS devices. If you own an iPhone, and then use the Messages application software to send short messages to Android, BlackBerry or WP users, the iOS system will default that the other party has no iMessage application, and then convert the information into SMS mode. At this point, the information is still displayed on the green background instead of the blue background.

However, even if you send a message to another iPhone, the background color is still green if the following three situations occur:

1) The iMessage service is not activated on your iPhone. You can click "Settings"-"Information" and see if this function is turned on. If enabled, you can also activate "Send by SMS", so that when iMessage is not used, the information will be sent by SMS, but you may have to pay the SMS fee of the operator. It should also be noted that when you activate the iMessage service, you need to log in with an Apple ID.

2)iMessage is not activated on the other device;

3) The current data network is unavailable. However, if your phone can connect to the language tower, it will default to SMS mode.

So, when should I choose iMessage or SMS mode?

Although short messages are small, picture messages consume a lot of data. If your phone plans to provide unlimited SMS, but the data traffic is limited, you'd better turn off iMessage and enable SMS. On the other hand, if you are texting with other iPhone users, but all you see is green background information, you should ask them to activate the iMessage service on their phones, so that you can experience many functions that iMessage brings you.