Hey, T-Mobile used GSM 1900 PCS. Sprint used CDMA 1900 PCS. 4G is Long Term Evolution (LTE) and is an evolution out of GSM. Essentially, when the wireless companies moved to 3G, the companies, Sprint & Verizon, had to migrate from CDMA to the GSM standard, UMTS, for data network because Qualcomm did not have their data evolution of CDMA ready to go, and the New World Order wanted GSM, their global standard. T-Mobile towers were originally PCS towers. No towers were retired. Last of the 2G networks were sunset last year, last of the 3G networks sunset this year. Only true 5G network is Verizon because they became the specification test market for the 3GPP Working Group, international wireless standards body. AT&T is deploying now but hamstrung by their financials --- TimeWarner merger fallout, same with T-Mobile, just a poor company living off the land like Sherman's march through the South. Both Verizon and AT&T do not have enough FCC Spectrum to take advantage of max capabilities of 5G, perhaps with frequency sharing by 2025. T-Mobile has the spectrum capability but not the money to deploy 5G because of their Sprint purchase. T-Mobile parent company, Duetsch Telecom just sold a European network, so they may save the day for T-Mobile USA. Then T-Mobile USA has to worry about plugging into the Duetsch Telecom Huawei equipment, which is verboten here in the USA. Did I fail to mention the USA Government sanctioned monopoly on the FCC 2500MHz frequencies, which was the plum in the Worldcom-Numarix-Nextel-Clearwire-Sprint mergers, and why T-Mobile took the lovers leap. Kind of smells like the AT&T run on TimeWarner, except a bit closer to their wireless home. The New World Order just doesn't quit, let's just hope they collapse. Oh well, here's to hope, without reference to Hope, Arkansas.