I respectfully disagree about Lingo ... their customer service sux... I have been owed a 29.95 refund from them for over a year, and continue to get dunning notices from their lawyer for something they owe me.
So, stay away from them ... get either Vonage or ATT Callvantage if you want VOIP.
BTW, I don't have any referral codes (so no financial interest, blah, blah, blah).