1. Payment amount exceeds the limit: when using WeChat change to pay, if the single or single-day expenditure exceeds a certain amount, such as 2000 yuan, the system will guide the user to install a digital certificate and increase the payment limit. After installing the digital certificate, when paying with change, you need to send a verification code to the mobile phone reserved by the bank to complete the security verification.

2. The payment amount is too large: when the payment amount is too large, the system will ask for identity verification, and at this time, it will also send a verification code to the bank to reserve a mobile phone.

3. Multi-account binding: If multiple WeChat payment accounts are bound to the bank card, when the daily limit of change payment of other accounts reaches a certain amount, the system may send a verification code to the bound mobile phone to ensure the security of payment. It should be noted that receiving the verification code does not mean that others are trying to steal funds, so don't worry. If the mobile phone number is newly bought, it is not excluded that there is a second number. It is recommended to contact the operator for verification.