Alas, VoIP services can be a crapshoot. Fortunately, most have month-to-month service plans, so you're not locked into a yearlong contract. And some of the major providers have a one-month free-trial offer (in fact, Vonage is offering that right now), but be sure to read the fine print carefully, as there are strict rules

about how and when to give cancellation notice in order to avoid termination fees and paying for an additional month. You might also consider keeping your landline while giving your VoIP service a trial run so that you won't have to deal with canceling and reordering regular phone service if VoIP doesn't work out for you. It's rough getting double-billed like that, but setting up a phone line ain't cheap either. You might also want to consider the SunRocket VoIP service. If you sign up for an entire year, it works out to about $16 per month, quite a deal compared to some other services. Even better, if you're dissatisfied, you can cancel at any time, and SunRocket will prorate the rest of your year and refund that money to you.

Finally, if you make long-distance calls only occasionally, consider a PC-to-PC service such as Skype. If you can convince the other party to sign up for Skype, too, your calls are free!