Why can't imessage be opened on both sides of iphone4s?

Only when the two parties are networked can they send imessage to each other.

To open imessage:

1, click Settings:

2, click on the message:

3. open imessage. If the icon is green, it will be open.

IMessage is an instant messaging software released by Apple WWDC20 1 1, which is built into iOS5 and Mac os x 10.8. You can send text, pictures, videos, address books and location information between iOS and Mac os devices, and support multi-person chat.

IMessage is different from SMS/MMS service of operators. Users only need the data support of WiFi or 3G network to complete communication. IMessage uses the new message reminder system of iOS and Mac os, which can directly push information to the other party's screen, regardless of whether the other party is in the game or locked. If both parties are using iMessage, you can even see the state of each other's speech.