How can African SMS go back to China?

Sometimes, if something is said through the mouth, sometimes people don't know how to answer it, but if it is in the form of information, the guy can think slowly and then answer. Sometimes, if it is inconvenient to talk on the phone, but it is necessary to tell it, a message will do! Also, nowadays, there are many idle people. Sometimes, it's boring to have nothing to do all afternoon. If these hours are spent on the phone, wow, the phone bill is really expensive! But if you send a message by mobile phone, you may only send a dozen or dozens in an afternoon. Plus, sending messages is a bilateral payment, and calling is a unilateral payment.