A TRAI official said that drive tests in seven cities across the country started on December 21 and are likely to end by January 8.
The cities are - Delhi, Mumbai, Surat, Kolkata, Pune, Bhubaneswar and Indore. Drive tests are conducted to assess coverage and quality of service of mobile networks.

Telecom Minister Ravi Shankar Prasad has said that call drop problem is improving and operators are putting up more tower sites.
The Minister last month said a total of 29,000 new telecom towers were installed by private telecom operators across the country after government took strong exception to the problem of call drops.
TRAI's response came on the pleas filed by telcos challenging the regulator's order mandating them to pay consumers Re 1 per call drop experienced on their network, subject to a cap of three a day.
TRAI had carried out special independent drive tests in Mumbai and Delhi in June and July and found the network quality below par.