You apparently didn't get everything from this thread. If you buy a Samsung make sure you buy a 2009 model from Verizon. Then try to switch carriers. You will have the same issue. There are two major phone technologies in use in the US, CDMA (Verizon and Sprint primarily) and GSM (AT&T and T-Mobile primarily). In 2009 when the iPhone 4 for Verizon was released their were no hybrid radio chips so you bought a CDMA phone or you bought a GSM phone. You have a CDMA phone. The only other carrier you could use that phone with is Sprint but they don't accept carry in phones (including Samsung).
With the iPhone 4s, and other companies phones, in 2010, cell phones did have the technology to be both a CDMA and GSM phone. But if you had a 4s or a Samsung, or an HTC or a Nokia with Verizon then you would have to get it unlocked through them and it would olnly be able to use foreign carriers. You could not take it to AT&T or T-Mobile. This is Verizon's policy.
With the iPhone 5 and including the 5c and 5s the GSM side of the iPhone is unlocked and can be used with any GSM carrier, no unlocking is necessary. You still can't use it with Sprint though, they still don't accept carry in phones of any manufacturer.