MTNL's scrip jumped 9.98 per cent to Rs 15.32 -- its upper circuit limit on the BSE.
At the NSE, the stock gained 9.71 per cent to touch its upper circuit at Rs 15.25.
Meanwhile, state-run telecom firms BSNL and MTNL today said that they are working jointly to offer free roaming service to their customers.
At present, MTNL and BSNL do not impose roaming charges for mobile internet services on each others customers.
Under the agreement signed today both the state-run firms have agreed to share their IT and other infrastructure required to jointly serve enterprise customers.
The infrastructure to be shared include buildings, ducts, mobile towers, International long distance and other facilities required for serving corporate clients.
Both BSNL and MTNL do not demarcate their revenue from enterprise business but BSNL estimates its revenue through this channel at around Rs 1,700 crore in the last fiscal.