The struggling state-owned NetOne whose subscriber numbers have remained mired at 350,000.
The additional capacity at Telecel takes its subscriber base to 700,000 after a recent addition of 100,000 lines by the network.
Econet Wireless remains on top after adding 600,000 new subscribers to reach 1.2 million.
The increase in mobile capacity by the two networks has taken place between February and August this year, and takes the country’s mobile penetration rate, which had been stuck at 10% for over a decade, to 18.75%.
In a statement, the company said it had completed the second phase of its expansion drive, replacing low capacity base stations with high capacity ones in all major urban areas.
“The elimination of these base stations has eliminated virtually all congestion in these areas and we are confident you will notice the difference immediately. It also means we cover more people with less base stations,” said Telecel.