How to check if my IPhone is unlocked?

I just bought an IPhone 4s On Amazon. Its supposed to be unlocked but when I went into Settings - About - it said the carrier is Verizon 16. Is there a way to check if this phone is unlocked. I don't have a sim card to try it out, and I tried that IMEI website but it always keeps telling me "service is unavailable please use paid version"
I wanna know whether the phone is unlocked or not cause I wanna jailbreak it and get a sim card from a carrier that's not as expensive as Verizon.
So my question: Is there a FREE way to check unlock status without needing a sim card or calling anywhere (I don't have a phone)

Yeah. Hope it doesn't come back as Verizon. Best luck.
http://iphoneimei.info/

This is a good checklist of things to verify
http://www.justtext.com/messageboards/20140127095337.html

Yeah those websites probably just stole your IMEI number so watch your phone bills VERY carefully. Easiest way would be to call Verizon and ask if it's locked to them.

Even if the phone is unlocked, it will show Verizon unless you put a SIM in or there's a Verizon SIM in. Remove the SIM, if any and use a different SIM card and see if the phone recognizes that SIM. If it does then your phone is unlocked. Jailbreaking the phone won't unlock the phone, you need to get the phone factory unlocked to get it to work with other SIM cards. If you need help with getting the phone factory unlocked, mail me.