Since 15th March 2023, the CEIR is available for all Indian states and Union Territories. It was first launched in September 2019 in Maharashtra, Dadra and Nagar Haveli, and Goa then expanded to Delhi in December 2019. The delay in the service being rolled out across India since its initial launch could be due to the pandemic.
About
CEIR stands for Central Equipment Identify Registry. It is a central system introduced to control the stolen mobile phone market. This system is managed by the DoT or Department of Telecommunications. Anybody who loses their phone can use this service.
Government says
The Government of India says, “With the aim to curtail the counterfeit mobile phone market and discourage mobile phone theft, protect consumer interest and facilitate law enforcement authorities for lawful interception, DoT intends to implement Central Equipment Identity Registry (CEIR) that connects to the IMEI database of all the mobile Operators. CEIR acts as a central system for all network Operators to share blacklisted mobile devices so that devices blacklisted in one network will not work on other networks even if the Subscriber Identity Module (SIM) card in the device is changed.”

How to use?
To use the feature, people need to go to the official website of CEIR or download the app from Apple App Store or Google Play Store. The best thing about this service is that it is free. If somebody loses their phone, they need to submit a request to CEIR and also file an FIR at the nearest police station. They would also need to get a duplicate SIM card for the lost number. It would be used as the primary contact number to receive OTP while filing the complaint.
People need to fill out the online form available on the app and website to submit the complaint. The form has mandatory fields to be filled like device model, mobile number, the location where the phone was lost, and IMEI 1 and 2 numbers. People need to submit a scanned copy of the FIR as well.
After a successful request submission, the user would receive a Request ID, and the phone would be blocked within 24 hours. Once the phone is blocked, it cannot be used on any mobile phone network throughout India.
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Check status and unblocking
The police would continue to track the lost or stolen device and people can also check the complaint status using the Request ID. Once the phone is found, it can be unblocked using the unblock option offered by CEIR. It would require the user to submit certain information along with the Request ID.