There are, in fact, a great many positive reasons to switch from POTS to VoIP:

1. It's cheaper. Way cheaper. From about $9.95 for the most basic service (still far better than POTS) to $39.95 for residential; business plans usually run from $49.95-to-$99.95 and include a separate fax number.

2. The free VoIP "modem" is shipped to you in 5 to 10 days; buy it at a store for same-day service and the VoIP firm will reimburse or credit it against your bill.

3. "Extra" services widely standard: VoiceMail, Caller ID, Call Waiting, 3-Way Conferencing, Call Forward, Repeat Dialing, Call Block, unlimited calling (local and LD) - in short, virtually every option ever offered - for an additional fee - by any POTS company.

4. No charge for incoming calls from anywhere, unlike US cellular providers; same for outgoing "local" calls (depending on plan; some use a cellular-style monthly minutes package).

5. With VoIP, "local" in North America almost always includes both the US and Canada; some also include Western Europe, parts of Asia and parts of Latin America. For those countries not included free, international plans are available for far less than standard LD companies. Or you can make occasional calls without a plan for far lower per-minute charges than most LD plans. This generally applies - more or less in reverse - for VoIP services in Europe, Asia and elsewhere, as well.

6. No computer needed, just plug a standard phone cable from the VoIP box to your regular desktop phone or portable base station.

7. Activate every phone jack in the house - just plug the VoIP modem into any existing wall jack, after first disconnecting your house's internal phone wiring from the POTS world at the phone box outside, probably on your front wall. This option generally is not available to apartment dwellers. Sorry.

8. Virtual Phone Numbers: For a low price (usually about $5), you can have a phone number in almost any area code, so friends or family can dial a local number that rings on your phone. You can't use it for outgoing calls because it isn't a "real" line.

9. Low-cost 800 Numbers: Want to make it free for a lot of callers without bankrupting you? Most VoIP providers offer cheap 800 numbers - free to the caller, fixed monthly rate for you (varies, but roughly $5 for the first 100 minutes each month, then 4.5-cents or so per minute beyond that).

10. Find Me: Some include a system that, if you don't answer, will call three or more other numbers you designate, in sequence or simultaneously, then go to voicemail if you still don't answer.

11. And this is THE KICKER: Take your home or office "phone" with you when you travel. Just pack the VoIP modem in your suitcase; on arrival, plug it into any high-speed Internet connection (hotel room, friend or relative's house, airport, whatever) and, bingo, you can place and, more importantly, receive calls made to your regular phone number. And that is true anywhere in the world (with charges based on your home location). Go to Bora Bora and someone calling your home or office number in Des Moines will never know you're not in Iowa when you answer; call someone and your usual Caller ID shows.

For every ying, of course, there must be a yang - so now for the downside:

1. If you have a cable Internet connection, your downline is 2 to 10 times faster than your upline. As a result, you may hear the other person clear as a bell and they may not hear you at all. This will lead to them hanging up on you (they don't know you're there) or demanding you "get off the speaker" or "hang up your cell and call me from a real phone". And those are the polite ones.

The VoIP companies insist 256K up should be more than enough for a clear signal; that does not appear to be the case in actual use. There are ways to overcome this, if you get a knowledgeable VoIP support tech.

2. High-speed connections vary in quality based on a host of factors, from how many other users are sharing that cable line to how far it is from the nearest DSL booster node. Which means day-to-day, even call-to-call, VoIP quality is going to vary, as well - sometimes to wild extremes.

3. When no one is speaking, there is a "dead" silence that makes most people, accustomed to the slight "buzz" of a POTS signal, think the connection has been broken. If you don't want to hear a constant "are you still there?", explain this to everyone at the start of any conversation.

4. If you try to "activate" a new credit card by calling via VoIP, the computer at the other end may insist you are not calling from your home phone. "Why?" is an as-yet unanswered question from the VoIP providers.

5. Never, ever, let anyone put you on silent hold. If your VoIP service doesn't hear something on that line for several minutes (how many seems to vary), it may simply disconnect you, apparently on the theory your phone is actually off the hook.

6. If your up-line signal is not strong enough, your call won't go through, leading to an annoyingly frequent "Your call cannot be completed at this time" recording.

7. Occasionally, your VoIP will just stop working. The fix varies slightly by provider, but basically involves a lot of unplugging and replugging of VoIP modem, router, cable/DSL connection, in a specific sequence provided by the VoIP company.

8. Last - and by far worst: If your Internet connection goes down for any reason, you have no phone service. Anyone depending entirely on VoIP is strongly encouraged to keep a cellphone handy (keeping in mind you can set VoIP up to automatically call your cell if you don't answer the VoIP line).

Bottom line: Commercial VoIP is a real telephone service, unlike computer-based "messengers" or even Skype (which clearly states it is not telephony); marks against, include no video (yet) and a lot of bugs yet to resolve. Still, at a savings of $30 to $100 a month, these problems aren't so severe you can't learn to live with them. It's a bigger issue for your office, but add a cellphone to the mix for back-up and you may soon join the growing number of consumers who have gone all-VoIP, with no intention of ever going to POTS again.