How to send short messages by fetion for free?

There is no charge for sending messages to the other party with Fetion mobile phone (but it must be a friend, otherwise there will be a charge). In addition, since you are a telecom operator, you can only send a fetion to a telecom mobile phone for free, and there is a charge for sending messages to China Unicom and China Mobile (according to the SMS tariff, how many messages did you send before, and now? )