What software can transmit short messages without network?

These softwares must be installed by both parties to receive messages. What you said is that you can directly use the traffic and send it to the other party's number in the form of SMS. This kind of software is not available in China (it is also deceptive, don't believe it), but there are several abroad. Heywire, it's easy to use, and it basically supports domestic numbers perfectly. I used it. However, when using it, we should pay attention to it. When sending a text message, be sure to indicate "Please don't reply". Otherwise, every time the other party replies to you, it will cost an extra yuan, because it is an international text message.