The notice sent to Bharti Airtel, Idea Cellular and Vodafone asks them to explain why penal action should not be taken against them.
"We have been given 60 days to respond to the notice," a senior executive of one of the firms told IANS.
The operators had entered into roaming agreements to offer 3G services such as video calling, mobile TV and multi-media gaming in areas where they did not have 3G spectrum.
The DoT had last December asked the operators to terminate their 3G roaming agreements calling it illegal. The department had also said the government was losing revenue because of these agreements.
The operators had then moved the tribunal challenging the DoT order, saying it would harm customers and investment in the sector. In July, the tribunal delivered a split verdict.
The two members of the bench, comprising chairman Justice (retd) S.B. Sinha and member P.K. Rastogi, had differing views on the order. One favouring the DoT claimed the roaming agreements were illegal, while the other supported the operators who had challenged it.
Get your daily dose of tech news, reviews, and insights, in under 80 characters on Gadgets 360 Turbo. Connect with fellow tech lovers on our Forum. Follow us on X, Facebook, WhatsApp, Threads and Google News for instant updates. Catch all the action on our YouTube channel.
Samsung Galaxy Watch 9 (44mm, LTE)
Starts from ₹44,999
Samsung Galaxy Watch 9 (40mm, LTE)
Starts from ₹37,999
Samsung Galaxy Watch 9 (40mm)
Starts from ₹37,999
Haier M70 Mini LED 65-inch
Starts from ₹74,990
CMF Buds Neo True Wireless Stereo (TWS) Earphones
Starts from ₹2,199
Xiaomi TV FX Mini LED 65
Starts from ₹64,999
IFA 2026: Lenovo Unveiled New IdeaPad, Yoga and ThinkBook Laptops
IFA 2026: Nvidia RTX Spark PCs, Local AI Tools Announced With October Launch Planned
Luna Band Now Available Globally: Check Price in India, Specifications and Features