Unlocked iPhone 5s

NO, All iPhones are not unlocked.

The Apple store sells unlocked iPhones, for the GSM side. As far as I know, CDMA carriers require you to buy your iPhone from them.

This article iPhone: About unlocking -> Wireless carrier support and features for iPhone - Apple Support states about

5. If account requirements are met, the carrier can unlock certain models of iPhone so that they can work internationally, but they'll still be restricted to that carrier in the United States and won't work on any other U.S. carriers. Contact your carrier for more details.

All Verizon LTE capable devices, including the iPhone 5, 5c, 5s, 6, and 6 Plus are GSM unlocked. That is legally required of them by the FCC in exchange for winning a spectrum auction a few years ago.

It can be used on any compatible GSM carrier.

If you want to use a CDMA carrier, however, you will need to purchase a phone specifically intended for use on that carrier. There is no way around that.

If you want to use StraightTalk and REQUIRE CDMA, then you will have to purchase a phone intended for use on StraightTalk. If they do not offer the model you want, you'll have to pick something else or choose a different carrier.

If they really sell unlocked iPhones, then it would be unlocked on the GSM side, but not the CDMA

Do you want the answer that you prefer, or the one we know to be true?

If you want he answer that pleases you, then yes it will work with anyone including straight talk.

Otherwise, the answer you have been given several times now stands.

They can sell you a Verizon CDMA phone. It will NOT work on StraightTalk's CDMA network. It will work on StraightTalk's GSM network.

There is no such thing a a CDMA "lock" in the way there is for a GSM lock. Rather, it's a matter of policy on the part of the carriers. A CDMA carrier will not activate a phone on their CDMA network that was not sold explicitly for use on their network.

Why not? Because there is no law requiring them to do so. There is no financial incentive for them to do so. They want you to buy a phone from them.

If that's something that causes you significant distress or inconvenience, then write or call your congressman. Nothing else is going to change that situation.

No one here can change that. If you want to use a discount CDMA carrier, then you will be limited by the options they offer.

Your options are:

Buy the phone they offer for use on their service.

Buy a different phone from Straight Talk that better meet your needs.

or

Sign up for service with Verizon and get the phone you want.

Take your pick.