So that I can better understand a couple of questions. Is your iPhone 4s a 3g or 4g? When did your landlord stop using this phone? If he used the phone in mid to late 2015 or later and it is a 4G LTE, then it is already unlocked and just needs a sim card from any carrier, imo. If he stopped using the phone prior to that period and began using a new phone, then there was no capability for Verizon to unlock, so therefore... good luck!