Is there a mobile phone couple card that sends messages to each other for free?

Mobile M-Zone and China Unicom now have services that can set home numbers.

In a different place, you only need to set up a short message monthly, and you can send short messages indefinitely.

If two people are in the same place, you can also set up a point-to-point monthly call. If you want to make a long-distance call, you'd better make a long-distance call with a cheaper card. Generally, the price of long-distance calls is maintained at around 1 cent.

For details, please consult the business halls in their respective locations.

I suggest you use a cheap card to make long-distance calls, and then set up a point-to-point SMS, with a family number every month. This is the most cost-effective and cheapest.