"Metro by T-Mobile " ---"MetroPCS previously operated the fifth largest mobile telecommunications network in the United States using code division multiple access (hence "PCS" in their name). " Hence I still don't know what the PCS stood for in MetroPCS's name. Oh, I just saw this: "All forms of CDMA use spread-spectrum process gain to allow receivers to partially discriminate against unwanted signals." So maybe PCS stands for "process code spectrum or signal". I'm glad "DeTeMobile" changed their name to "T Mobile".
Personal Communications Services. I believe it was the official name for a certain segment of the wireless spectrum auctioned by the FCC in the late '90s.