move my new Galay S7 Verizon SIM card into my old Galaxy S6 phone - was AT&T

[AC Question]

Recently switched to Verizon (new Galaxy S7) from AT&T (Galaxy S6).
I like the S6 phone better. Can I move the VZ S7 SIMM card . . . into my old ATT S6 phone?

 

[B. Diddy]

Welcome to Android Central! I don't think so. The AT&T S6 is GSM only, while Verizon still relies on the CDMA network for voice calls. Verizon has been expanding its VoLTE (Voice over LTE) network, so if the phone supported Verizon's LTE bands well, then it's theoretically possible that the phone would work ok--but the AT&T S6 only overlaps with Verizon's LTE bands on band 2. Verizon relies mostly on band 13, so connection would be unreliable.

Samsung Galaxy S6, 32GB†, (AT&T), Gold Platinum
Cheat sheet: which 4G LTE bands do AT&T, Verizon, T-Mobile and Sprint use in the USA?

 

[Rukbat]

And the S6 is probably SIM-locked, so you'd have to buy the unlock code (unless it's still on an AT&T plan - then AT&T will give it to you).