China Mobile and China Unicom send short messages. Do I have to pay extra for the number of messages I send? I need the latest information.

The key depends on whether the number of short messages in the mobile phone package is in the network. If it is within the network, it only includes messages sent to mobile devices. If there is no limit, there is no extra charge for sending messages to Unicom. I suggest you call the mobile customer service number 10086 to find out in detail whether the number of short messages included in your mobile phone package has any restrictions on the network of the receiver.