The CDMA giant has only one-third the install base of the largest smartphone carrier in the U.S. at only 53 million users. Should it merge with T-Mobile, the combined user count would still be millions fewer than Verizon and AT&T, but the combined resources would allow Deutsche Telekom and SoftBank to better compete in the wake of 5G technology. Talks between T-Mobile and Sprint have been on and off for the past 4 years due to anti-trust concerns.
https://www.notebookcheck.net/T-Mobile-and-Sprint-are-closer-than-ever-to-a-potential-merger.301556.0.html