MetroPCS and T-Mobile owner Deutsche Telekom in talks
Deutsche Telekom has said it is in talks to buy MetroPCS and merge the US mobile carrier with its T-Mobile USA unit.
Shares in MetroPCS jumped 17%.
The German giant warned that there are still "major issues" to be discussed over the potential takeover.
This comes after US telecoms giant AT&T had to end its $39bn (£24bn) bid in December to buy T-Mobile USA, having run into fierce objections from the government.
MetroPCS says it is the fifth-largest US wireless carrier and has more than 9 million subscribers.
If AT&T had bought T-Mobile USA from Deutsche Telekom, it would have become the largest US cellphone company.
The US Justice Department moved to block the merger in August 2011, saying it would reduce competition and lead to higher prices.
T-Mobile USA is the fourth-largest mobile carrier, while AT&T is currently the country's second-largest.
The German firm's US unit has more than 33 million customers.