Since the iPad was first released, sophisticated users have been getting smart to avoid unnecessarily additional data costs by tethering 3G phones to the iPad when a Wi-Fi signal is NOT available. Android smartphone users have it easiest tethering ipad to a 4G phone especially on T-Mobile. Not a surprise to see that AT&T has not been very consumer friendly to iPhone users and has made it very difficult for their data subscribers on the iPhone to tether any devices to their 3G service. However, the Wi-Fi only iPad oan be used on the 3G network of any carrier to avoid purchasing another expensive data plan if they are already on Sprint, Verizon, T-Mobile or a smaller regional carrier. So here is a great option especially if your carrier never intends to cap your data plan. Android users will likely be the heaviest adopters of this since most are already on other networks.