Obtain the specific model number of that phone, look up what frequencies it supports on the Apple site (they have full information in that regard) and then compare it to the carrier frequencies shown on this blog posting: » tl:dr-- your phone must support LTE bands 4 (1700) and 13 (700). Iphone 3gs Factory Unlock Software Free Download here. Band 13 is Verizon's primary LTE band. Band 4, which Verizon markets as XLTE, is used to provide increased speed and capacity in urban areas. The other frequencies that Verizon uses are 850 Mhz and 1900 Mhz for voice, 1xRTT (2G) and EVDO (3G) data. Said by: Verizon won't activate an unlocked phone on it's network? At&t Go Phone Network Unlock Code. Two things. Verizon and sprint still operate locked cdma networks.
Since the iphone does its voice over cdma they won't let it on the locked network unless they sold it. The tmobile iphones may not have the cdma chipsets (of course even if they do since verizon/sprint didnt sell the serial number they won't let it on their network). Verizon cannot lock its lte down. So in theory you could activate a verizon lte sim somewhere and then move that over to the iphone 5s.