wifi charges

[Odeezie]

So I've done a search and I didn't pull up anything solid so hopefully this hasn't been covered much already. Basically, I got my first months bill and was charged for "wireless web anytime minutes - PCS Data" for around $50. I DO NOT have vision enabled. I called customer service and they had tech support explain the situation to me. Basically, they said that even when you connect to wifi spots, the sprint data network is still being used somehow. She called it IPB or was it IBP? Either way, I was completely confused as to how that works. I asked a guy at the sprint store and he said that sometimes the sprint data network is used to help "buffer" slow or bad wifi connections. How is this even possible? I'm not saying I don't believe them but it's just retarded to me that you would have wifi capability while having a data plan. I feel pretty damn cheated!! One of the reasons why I bought the phone was so I could use wifi instead of paying for a data package!! Can anyone explain to me how this technology works??

cn: wifi usage causes data usage on the sprint data network. How?