Not cool! Lets get the battery figured out. Does this happen while device is on charger? What do you mean by locking up? Since it is getting hot, we recommend to take it into a Verizon Wireless store with the charger and accessories for a hands on evaluation.
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I had the same issue with my I Phone 4 S getting hot not to hot to burn you but hot by the sim card holder and hot were the charger goes in I took it to the Apple store and the did a check on it they did a check on the phone and they found out why its getting hot bc of constant use I eliminated all my usage and cleared out the usage and it solved the problem for a little while it still gets hot I may take vzw customer services suggestion bring it into a corporate Verizon Wireless store along with my charger and see if the Verizon Wireless Corporate store techs can figure out why it gets hot
What's the signal Level on your 4S is it really low all the Time? It may be you're far enough away from a Tower the phone is trying to stay connected to it.. you might try if you have it available.. try Wi-Fi for your Data connecting see if that helps the Temperature levels go down to a safer level