The iPhone 4S on Verizon is an EVDO/CDMA only phone so it would only be programmed with an ESN and dialing *228 send. LTE didn't come until the iPhone 5. If it has a SIM slot it's only for international. Then you'd have to validate it on the ESN side. The IMEI is also for international use only on that particular device.
Edit: that particular phone will function without a SIM card as its provisioned through a software download. You just couldn't use it internationally. And if it was used internationally the SIM card would have to be registered with VZW with international dialing and roaming enabled.