The Department of Posts under the Ministry of Communications and the Telecom Regulatory Authority of India (TRAI) have joined hands for India's largest telecom network performance survey at the village level, covering 5.68 lakh villages. More than 1.4 lakh Gramin Dak Sevaks, the rural postal workers, will use a TRAI-built Android app during their regular deliveries to rate network coverage of Airtel, Jio, Vi and BSNL. The detailed field data will help identify 'not-spots', places with no coverage at all, and guide future investment in telecom infrastructure.