Sprint shares jumped 5.3 percent in after-hours trading, while shares of T-Mobile rose 3.3 percent.
Last week, reports surfaced that SoftBank was planning to break off negotiations over disagreements on which side would control the combined company. SoftBank, a Japanese conglomerate, was reportedly hesitant to give up control of Sprint.
But CNBC's David Faber reported that SoftBank was not preparing to give up just yet. The proposal from earlier this year was for a stock-for-stock deal that would give Deutsche Telekom, T-Mobile's parent, control.
The telecommunications companies could reach a deal within weeks, the WSJ said.