Laptop magazine has a review of Fring, Talkster, Nimbuzz and Barablu. These four apps turn your good old cell phone into an internet phone and more. Of the four, Nimbuzz is new to me and Barablu I haven’t tried yet. Fring and Talkster I’ve used and quite like, although I think having a great handset makes all the difference. I wouldn’t bother with any of these if I didn’t have the Nokia N80i to test with.
The review does a good job of capturing the typical setup process for all applications, and gives both the pros and cons of usability, call quality and the like. Author Joanna Stern points out that “regardless of which mobile VoIP service you use, you’re going to need an unlimited data plan, which costs anywhere from $5.99 per month (T-Mobile) to $24.99 (Cingular)”.
Edited May 17, 2007:
James Wanless of Talkster clarified for me that their service in fact does not require a data plan: