The stock zoomed 19.88 per cent to settle at Rs 19.90 -- its highest trading permissible limit for the day on the BSE.
On the NSE, the scrip soared 19.94 per cent to touch its upper circuit limit of Rs 19.85.
The company's market value rose by Rs 208.7 crore to Rs 1,253.70 crore.
On the volume front, 61.74 lakh shares of the company changed hands at the BSE and over two crore shares were traded at the NSE during the day.
According to media reports, the government is planning to delist the stock before merging the telecom operator with Bharat Sanchar Nigam Ltd.
Meanwhile, in the stock market the benchmark BSE Sensex ended 146.99 points up at 28,092.79.