With all the marvels of my Pocket PC (an HTC 8925), lately I've been questioning whether or not I need true calling service with AT&T. Could I cancel my phone service, stick with just an unlimited data plan, and get by using VoIP for my calls? The monthly savings are tempting, so I decided to research the benefits and drawbacks of using only Skype for calls.
As of November, I've had service with AT&T to provide 450 Anytime & 5000 nights/weekend minutes and their Unlimited data plan. The total monthly bill is $65 (Time Warner perk). The break down is more or less half phone plan, half data plan. So theoretically, switching to all VoIP would be cost effective for anything less than $30.
Skype Pro costs $3. That's it. You can make calls to other Skype users (worldwide), and to U.S. land lines and mobile phones for $3 a month. If you want to receive calls, too, you'll need a Skype online number for others to dial. Total cost of that (for Pro users) is $30 a year, or $2.50 a month. Yikes. Financially, this is a much better deal.
The big questions reside around how you use your mobile phone service. Skype has three major limitations: you must be in WiFi or 3G network coverage, no free SMS, and emergency calls don't work quite as well.
SMS... this isn't a deal breaker to me, since you can send SMS for pennies if you need it. MMS should be less affected because any device capable of receiving an MMS can probably check e-mail, too. I know other people who live and die by SMS. Skype is not the service for them.
The problem with making emergency calls, such as 9-1-1, from a VoIP device is that the responders have no idea where you are unless you can tell them. With a cell phone, they can calculate your position with cell towers or look up your carrier and access your address. To make your only phone a VoIP device means taking on a significant risk that you might be in trouble and have no way to contact emergency services.
That leads into the other limitation- range of service. If you aren't in a WiFi hot spot or inside 3G network coverage, you don't have a phone, period. I personally haven't tried to use Skype in an EDGE environment, but the Skype website says 3G is a requirement. 90% of my time is spent at the office, at home, or in the perimeter of Atlanta... so this shouldn't be a problem for me, but I'm still concerned. That first time I'd want to make a call and can't would really tick me off. I wouldn't be out of contact, far from it, and odds are good that I'm with other people who have phones, but it's still a severe inconvenience. Though I suppose to save $25/month, it may be worthwhile.
To summarize, the cost benefit is there in spades. I'm looking at saving $25 x 12 = $300/year. I'm locked into a 2-year contract which expires this summer. Before then, I'll have to give Skype Pro a thorough review. If it passes the test, I'll discontinue phone service in July and attempt to get by on Skype and AT&T 3G alone.