Anonymous SMS: Can the police find out who sent it?

If you send a text message by mobile phone, the mobile phone has a phone number, and all phone numbers are registered by real name. Check with the operator and you'll know who it is. If you send text messages on a computer, the network used by the computer has an IP address. If you know the IP address, you can find the user, and anonymous short messages can find out where they are sent at once, and who sent them.