Why do you need other mobile phone numbers to send verification codes when your mobile phone number is cancelled?

After the mobile phone number is cancelled, other mobile phone numbers can still receive the verification code. Because after the cancellation of the mobile phone number, the relevant operators will completely cancel the mobile phone number, and the mobile phone number will become an empty number and cannot receive short messages. However, if the mobile phone number is already bound with other mobile phone numbers, the verification code will be sent to the bound mobile phone number. Therefore, when the mobile phone number is cancelled, if the mobile phone number has been bound to other mobile phone numbers, other mobile phone numbers can still receive the verification code.