The requirement, known as SIM-binding, means an account must remain connected to the active SIM associated with its registered mobile number.
Unlike a one-time text verification code, this creates an ongoing link between the messaging service and the SIM installed in the device.
Messaging accounts can still work after the associated SIM is removed or deactivated.
DoT says criminals exploit this gap to operate accounts remotely, including from outside India, while using Indian numbers for phishing, investment fraud and fake government calls.
WhatsApp May Stop Working Without Registered SIM Under New Rules
WhatsApp users may need to keep their registered SIM active, affecting secondary phones, tablets, and SIM-free devices.
cybersecuritynews.com