Is it really free to send text messages by phone?

As long as lz's sim card can receive short messages normally, there is enough roaming-free data traffic, and answering calls is free (no roaming charges or other answering fees), then lz's use of micro will mobile phones is free. In other words, as long as the above three conditions are met, lz will only consume data traffic and free call duration when making calls with micro-will, and will not generate other expenses.