I would like to ask heroes, why does China Mobile have a 12 digit phone?

One possibility is that the number is 1 1 bit, and the last bit is redundant. When making a call, the mobile phone program automatically dials the first number 1 1, and the call is successful. However, when sending a short message, the mobile phone program takes 12 digits, and the short message center rejects this number, and the sending fails.

I suggest you try to delete the last one when you send a text message.