Human intelligence was used and various police teams in Central Range of Delhi Police were sent to far flung places in West Bengal, Uttar Pradesh, Punjab, Rajasthan and North East for recovery of stolen mobile phones, said S K Gautam, Joint Commissioner of Central Range.
Most of the stolen phones had found their way in the grey market and were sold at discounted prices.
Previously the retailers managed to change all other traces of a phone being stolen but they could never tamper with the IMEI. But now the technology of tampering with the IMEI have entered the grey market, the officer said.