The difference between blue font and green SMS on iphone

The difference between the blue font of iphone SMS and the green SMS lies in the different cost.

Blue, is iMessage message (free, but requires networking: WiFi, data network can be; This function should be turned on in settings and SMS); The green word is the SMS or MMS of the operator. If you don't apply for the relevant free package, you will be charged. Blue is Apple's IMG, which is free information. If both the sender and the other party use Apple devices and the img function is turned on, it is free to send messages to each other when they are connected to the network. Sometimes, due to network problems, it will be automatically converted into short messages sent by operators, and then turn green.