Complex sentence: Of these, AT&T and T-Mobile use the GSM standard, while Verizon, US Cellular and Sprint use CDMA, all are currently rolling out networks using LTE as their future standard.
Split into simpler sentences: Of these, AT&T and T-Mobile use the GSM standard, while Verizon, US Cellular and Sprint use CDMA. All are currently rolling out networks using LTE as their future standard.