John Legere, chief executive officer of T-Mobile US.

Talks between Sprint and T-Mobile for a possible merger continue despite differences on key issues, sources told CNBC.

Last week, reports surfaced that SoftBank, the Japanese conglomerate that controls Sprint, was planning to end talks with T-Mobile, whose parent is Deutsche Telekom.

Deutsche Telekom representatives are believed to visit SoftBank's Masa Son this weekend, sources told CNBC.

The talks had lost momentum over price and governance issues.

— Evelyn Cheng contributed to this report.