Verizon phones are CDMA and do not use a sim card. There is a BYOP plan to bring a Verizon phone to Straight Talk and be on VZW's non-roaming network however.
However, some certain VZW LTE phones do have a gsm sim card slot for international travel. The iPhone 5 is one of them and it is unlocked. I'm sure their LTE Androids do as well, but whether or not it is unlocked, I don't know.
What phone are you trying to bring?