One of the many, many problems I have with Ooma is that random strangers could be using your landline to make local calls. That, for a number of reasons, just doesn't sit well with me.

PhoneGnome, which basically does a lot of what Ooma does, now has a feature where you can allow specific PhoneGnome users to remotely use your landline to complete certain calls. It's a pay service, but at least you know exactly who could be using your phone line.