Customers of Comcast’s Xfinity service will soon be able to use a Comcast app to make phone calls from their home number over the Internet on any Wi-Fi network. So if you’re out and about, in theory, it just got a lot easier to make calls from, say, an iPod Touch without using a cell phone network. Just find a Wi-Fi signal. It’s a system called Voice Over Internet Protocol or VOIP. But is it reliable? Plus, IBM has banned the use of Apple’s voice-controlled personal assistant Siri from the company’s campus. We chat with Siri about it all.