Using Another Provider's Phone With Verizon, Sprint, or US Cellular
Verizon's phones and network are CDMA, which doesn't use sim cards.
CDMA phones do not use sim cards, while GSM phones do.
CDMA and GSM are different technologies that are incompatible with each other.
The term "unlocking" referring to an unlocked phone is used when discussing GSM and iDEN phones.
There are other CDMA providers besides Verizon, which include Sprint and US Cellular.
Verizon will only activate another Verizon phone. A non-Verizon CDMA phone's ESN number will not be in Verizon's database of phones, and therefore, Verizon will not activate it.