Goa, Dec. 2 -- Launched in January, the Sanchar Saathi app allowed users to check a phone's IMEI, report lost or stolen devices, and flag suspected fraud communications. The IMEI is a unique 15-digit code that identifies a handset on mobile networks, and the government said duplicate or spoofed numbers posed a serious threat to telecom cybersecurity. It also noted that India's large second-hand market often saw stolen or blacklisted phones being resold, leaving unsuspecting buyers at risk.

To address this, India ordered all new smartphones to come with the app pre-installed within 90 days, and made it visible during device set-up without allowing users to disable its functions. Smartphone makers were told to push the app through software...