It's not as cheap as Sunrocket/Viatalk, but about the same as Vonage's unlimited plan. And a friend of mine who has it likes it a lot. It also seems it's a little less likely to disappear, since as much as AT&T sucks, they're probably not going anywhere any time soon.
Now that we've thrown 'em off the trail, use the form below to get in touch with the people at Engadget. Please fill in all of the required fields because they're required.
AT&T has a largely-unadvertised VOIP service called Callvantage:
https://www.callvantage.att.com/
It's not as cheap as Sunrocket/Viatalk, but about the same as Vonage's unlimited plan. And a friend of mine who has it likes it a lot. It also seems it's a little less likely to disappear, since as much as AT&T sucks, they're probably not going anywhere any time soon.