Questions about iphone with/out the SIM card

Question

Someone is selling me his iPhone and I might or might not use it as a phone.
If I don't put my At&t SIM card in can I still use Safari (over Wifi) and the ipod function?
If I do put the SIM card in can I use all the functions of the iphone without a data plan?

Answer 1

If you purchase a used iPhone and take the iPhone with you to an at&t corporate store, more than likely at&t won't charge you for a new SIM card to activate the iPhone with at&t.
When activating an iPhone with at&t, as a new subscriber or as an existing subscriber, selecting the unlimited data plan for the iPhone, which includes 200 SMS, is required at that time. If you are an existing at&t subscriber, this replaces any existing data plan and SMS plan you currently have and are using with an existing phone with at&t.
Some have reported that were able to cancel the unlimited data plan after the activation process, but this will eliminate visual voicemail - which are downloaded to the iPhone via at&t's data network only, and if downloaded anyway without the data plan, you will be charged by the KB for each messages downloaded to the iPhone. The same when accessing the internet other than when connected via wi-fi with the iPhone. If you access the internet via at&t's data or EDGE network without the unlimited data plan, you will be charged by the KB for all data downloaded and uploaded - when checking email, web browsing with Safari, Maps access, youtube, etc., etc.
You say you won't use the unlimited data plan, but you will likely want or need to use it more often than you realize. If you don't want the unlimited data plan, you may want to consider purchasing an iPod Touch instead.