Buried in Apple's two-hour keynote today was the exciting fact that iOS 8 will save you cell plan minutes with Wi-Fi calling — but that feature will likely depend on carriers to allow it. T-Mobile was quick to announce it will be the first US provider to support Wi-Fi calling, saying in a blog post that iPhone users would soon join the 5 million T-Mobile customers who already use Wi-Fi calling on their devices. It's not a particularly surprising move for T-Mobile, given its "uncarrier" campaign of customer-friendly moves and the fact that the company has enabled Wi-Fi calling for seven years. What would really be news is if giants Verizon and AT&T announced support for Wi-Fi calling — but given how long it took them to support FaceTime over cellular connections, you probably shouldn't hold your breath.