Using an iPhone as an iPod Touch
Recently I was looking into purchasing a iPod Touch. Can I purchase a used iPhone (already activated) and use it as a Touch? I did some research from Apple about it and ran across the following article: support.apple.com/kb/HT3406
The article clears up the question somewhat, but not fully. I realize that a SIM card will be necessary to upgrade the iPhone. However, can I just use a friends iPhone SIM card to activate the phone after upgrades? Do I have to continue to use the same SIM card on each upgrade or can I use any iPhone SIM card every time I upgrade? I hope to be able to purchase a used iPhone (without a sim card). I work with iPhone app developers, so borrowing an activated iPhone SIM card on upgrade will not be a problem.
I would like to purchase an iPhone instead of an iPod Touch because they are generally cheaper (1/2-2/3 the cost used...) since people purchase them at a low cost when bundled with a cellphone plan. Also the iPhone has a GPS and if, in the future, I decide I want to pay for a data plan and activate the phone, I have that option.
Any help on this matter would be greatly appreciated. Thanks.