I recently got a new 6+ and I'm very happy with it. My old 4S 16Gb is now sitting unused on a dresser at home and I'm wondering what I should do with it. The 4S is in excellent condition with no scratches on the screen or sides and only a few minor scratches on the back. It is an unlocked Verizon version.
The Verizon iP4s is not unlocked unless you get Verizon to unlock it and then it is only unlocked for international use. The Verizon iP4s won't work on TMobile or AT&T even if unlocked internationally but still, international buyers or those who use their phones internationally are interested in purchasing them.
There may be some way to unlock them for domestic GSM use if you jailbreak and pay for a service, idk, but if all you did was get Verizon to unlock the phone, it is only unlocked for international use.
1. Keep the 4S as a backup and use it like a quasi iPod Touch?
If you have a use for it as an iPod touch-like device then that is a good idea.
2. Sell it on Ebay or Craigslist?
This is what I would do (except I would sell on swappa) unless you don't have any other backup devices and don't carry insurance. If you don't have any other b/u devices and don't carry insurance, it is worth keeping your iP4s IMO unless you can afford to go out and buy yourself a brand new phone if you lose yours.
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3. Somehow get something for it from Verizon?
Well you missed the great trade-in deal at launch when Verizon was giving $200 for an iP4 or an iP4s. Now I think you would only get around $70 or so for it. They have a trade-in site:
https://www.trade-in.vzw.com/home.php5?c=en-us
But they do periodically have those "trade-in any working smartphone" promos if you buy a new device.
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4. Donate it to a worthy organization?
Which one would have use for a 3G smartphone? Flip phones, sure, I can see giving those to domestic violence shelters or for military but a 3G device requires an expensive data plan to use but yet you would only get 3G speeds. Verizon's 3G speeds are terrible. Who is crazy enough to pay for a data plan nowadays and only get 3G speeds on Verizon?