Core Viewpoint - The article highlights the risks associated with not unlinking accounts from old phone numbers, which can lead to unauthorized access and potential financial loss when these numbers are reissued to new users [1][3]. Group 1: Risks of Unlinked Accounts - A case in Inner Mongolia illustrates that a user lost access to their WeChat account containing 100,000 yuan due to their old phone number being reissued without unlinking it from the account [1]. - The reissuance of phone numbers, termed "secondary numbers," occurs 90 days after deactivation, allowing new users to access accounts if the original owner has not unlinked them [1][3]. Group 2: Services and Solutions - Users can check if a new number is a "secondary number" through a service called "Secondary Number Renewal," which allows for the unbinding of historical account links [5]. - The "One Certificate Inquiry 2.0" service enables users to check all internet accounts linked to their phone number, enhancing security [7]. Group 3: Best Practices for Number Change - It is recommended to prioritize unlinking accounts related to payment, social media, and cloud storage before deactivating a phone number [12]. - After successfully unlinking and deactivating a number, physical destruction of the SIM card is advised to prevent unauthorized reuse [14]. Group 4: Data Security for Old Devices - Old electronic devices may contain sensitive personal information, and proper cleaning is necessary before disposal to avoid data leaks [15]. - Steps for cleaning old devices include ensuring that personal, financial, and work-related information is securely erased [18].

Core Viewpoint - The article highlights the risks associated with not unlinking old phone numbers from accounts, which can lead to unauthorized access and potential financial loss when the number is reassigned to someone else [1][4]. Group 1: Incident Overview - A case was reported where an individual lost access to their WeChat account containing 100,000 yuan due to their old phone number being reassigned after not being unlinked [1][2]. - The police were able to recover the account and funds after identifying the new user [2]. Group 2: Regulations and Risks - According to national telecommunications regulations, phone numbers can be reassigned 90 days after cancellation, referred to as "secondary numbers" [2][4]. - The practice of reassigning numbers is a common method to optimize communication resources but poses privacy and security risks if the original owner has not unlinked their accounts [4]. Group 3: User Guidance - Users can check if a new number is a "secondary number" through a service provided by major telecom operators and internet platforms, which allows for easy unbinding of previous account associations [6][10]. - It is recommended to prioritize unlinking important accounts, such as payment and social media, before canceling the old number [12]. Group 4: Security Measures - After unlinking and canceling a number, it is advised to physically destroy the SIM card to prevent unauthorized use [13]. - Old electronic devices should also be properly cleaned to avoid leaking personal information, including financial and work-related data [13]. Group 5: Final Recommendations - The article emphasizes a three-step process for changing phone numbers: query, unlink, and destroy, to safeguard personal information [15].