Miami-based VoIP phone service company NetTalk.com has struggled to compete with better-known rival MagicJack. But the company got a major boost in October when Walmart began selling its NetTalk Duo. The device, which costs around $70 and includes one year of service, connects a regular telephone to a cable modem or DSL modem, letting users make free calls to the U.S. and Canada and discounted international calls. NetTalk.com originally required users to make calls through their computers, but in 2010 it launched NetTalk Duo, taking the computer out of the equation. During the first three quarters of 2011, revenue was $1.7 million, up from $730,000 from the year-earlier period. But it also lost more money during those three quarters — more than $28 million, compared to a 2010 net loss of $6.3 million.

[Note: In late December, NetTalk announced it was reducing the retail price of the DUO from $69.95 to $49.95]