Phone numbers are widely used as unique identifiers in apps and online services because each number is generally tied to one individual. But what if two different accounts try to use the same phone number? This situation can cause conflicts, security risks, and user experience issues. Let’s explore what typically happens and why phone number uniqueness is important.
1. Phone Numbers Are Meant to Be Unique Identifiers
Most apps and services require that each phone number is associated with only one account. The number acts like a digital ID, so allowing two accounts with the same number could cause confusion and compromise security.
2. Account Registration and Verification
When you register an account with a phone number, the app usually sends a verification code via SMS to that number. This ensures that the person registering actually owns or controls the phone number.
If two people try to register different accounts with the same phone number, only the one who receives and enters the verification code can complete the process.
If the number is already linked to an existing account, the app will usually prevent the creation of a second account with that number.
In some cases, if the user tries to register a new account with a number already in use, the app may prompt to log into the existing account instead or send a password reset link.
3. What Happens When Two Accounts Somehow Share One Number?
In rare situations—often due to glitches, number recycling by carriers, or intentional misuse—two accounts might end up linked to the same number. Here’s what can happen:
a. Account Access Conflicts
Receiving SMS verification codes or account recovery codes may be sent to the same phone number but intended for different accounts.
This can cause confusion and security risks, as one person may gain recent mobile phone number data unauthorized access to the other’s account through the shared number.
b. Privacy Issues
Notifications, messages, or sensitive information could be delivered to the wrong user.
Contacts or friends might get mixed up or confused about who they are actually communicating with.
4. Number Recycling and Its Impact
Mobile carriers recycle phone numbers after a period of inactivity. When a number is reassigned:
The new owner might receive verification codes or messages meant for the previous owner’s accounts.
If the previous owner’s accounts were not updated or deleted, this can cause account takeover risks.
To mitigate this, apps often require periodic re-verification or allow users to change their linked phone number.
5. Security Measures Taken by Apps
To avoid issues with multiple accounts sharing a number, apps implement various safeguards:
One number, one account policy: New registrations with an existing number are blocked.
Account recovery procedures: Require additional identity verification beyond just phone number access.
Phone number change features: Let users update their number to maintain account security.
Alert systems: Notify users if suspicious activity or multiple verifications happen on their number.
6. User Actions if Number Conflict Occurs
If you suspect your number is linked to someone else’s account:
Contact the app’s customer support to resolve the conflict.
Change your phone number on your accounts if possible.
Enable two-factor authentication (2FA) for added security.
Notify your carrier about potential number recycling or fraud.
Conclusion
In most cases, apps ensure that a single phone number can only be linked to one account, maintaining security and clarity. However, when two accounts share a number due to technical issues, number recycling, or misuse, it can lead to privacy breaches and confusion. Users and service providers must take precautions to keep phone number ownership clear and secure.