When I first heard that T-mobile was offering a VoIP service, frankly, I wondered what could cause them to do such a thing, and what would motivate a customer to buy it. I've never paid much attention to VoIP because I've gotten so used to being mobile, 100% of the time. I went to my local T-Mobile store to check it out, and saw that they were pushing it as the hot new product.

The service is $10 a month for unlimited calls, to anywhere in the States and Canada. This is obviously great deal, but to qualify for the service, you must already have a $39.99 or higher rate plan with T-Mo. The first benefit that came to mind was downgrading my cell plan without getting overage fees for family calls. That's where those surprise minutes at the end of the month usually come from, for me. I went home, looked at my last five or six bills, ran the numbers, and found that it would save me roughly $30 per average month, based on family calls alone ? without changing any of my three cell plans.

One of the selling points for the @Home service is that you get discounted International calling. So, I started thinking about my wife, who calls Southeast Asia on a regular basis, and a friend whose mother lives in Guatemala. Both use phone cards, because the total cost of the cell minutes used in calling the card's 1-800 number, plus the per-minute fee of the card, on top of the card connect fees, is much less than the cost of calling their loved ones directly from a cell or landline.

I called T-Mo for some clarification on the international savings. The two T-Mobile International plans are $5.00 a month whether added to a cell plan or the @Home service, but they are considered different plans. After comparing the rates for several countries with the agent, going back and forth between the standard cellular international plan and the @Home international plan, I found that the @Home service would not save me any money on international calls.

The few places I was interested in calling were the exact same rate regardless of whether they were made on a cell or home phone. The sales agent assured me that there were many countries for which a large discount is available. Off the top of her head, she recalled that Peru was a great deal for @Home users.

I checked it out, and yes indeed, it is a deal. Calling Peru with the @Home service costs $0.19 a minute when calling a landline, and $0.39 a minute to a mobile. Calling Peru from a T-mobile cell phone costs $0.25 per minute if the destination uses a landline and $0.44 a minute if it's mobile. Remember, these rates are for those who have the $5.00 monthly international plan added to their service. Without it, you can basically quadruple the fees listed above. If you spend more than a few minutes calling other countries each month, the plans are definitely worth looking into.

You can see if @Home would save you on international calls by comparing the lists here. The difference in the cost of calling a landline versus a mobile number can be substantial, so beware.

Even though I won't be saving on international calls, I still decided to give @Home a spin, because my minute usage is out of control and upgrading my plan each month is getting pretty pricey. Having the back-up phone at my home for $10 a month, just in case I hit that minute barrier, is reassuring. It turns out that I use my cell at home more than I had thought, and I was able to cut the costs of my cell plans in half by switching our three lines to a low-minute family plan. Plus, I got a very cool wireless router for $50 (and a two-year agreement). The challenge now is to break the habit of calling with my cell when I'm at my home.

I'll be back with a full review in a month or two, once I've given the service an opportunity to be problematic (nothing yet), and after I've seen a few bills.