A funny thing happened recently on the way to that elusive and much-maligned land called Internet Convergence: Auction giant eBay Inc. did a little shopping of its own and suddenly became one of the world's largest phone companies.

The buyout by eBay of Skype Technologies SA, the world leader in telephony on the Internet, was so completely unexpected that many talking heads are still struck dumb. But a number of Wall Street and techno-pundits have found their voices and are loudly comparing the deal to ridiculous transactions from dot-com days of yore.

At first blush, it does seem a bit frothy to pay $2.6 billion for a company that few Americans ever heard of, that uses nothing but downloadable software to make phone calls, and that gives much of its service away for free.

In less than three years, Skype has amassed more than 54 million customers. But with Skype's projected revenue of $60 million this year, and its costs and technology closely guarded, eBay is shelling out a hefty chunk of what some pundits are calling dumb money.

Maybe. It's certainly hard to know just how to value an emerging business like Skype, short of, say, putting it up for auction on eBay. But is this deal really such a crazy gamble?

Perhaps one way to get a handle on the question would be to compare it with a bigger tech deal that went down on the same day, which no one even blinked at: the $5.53 billion purchase of Siebel Systems Inc. by database giant Oracle Corp.

This involves a smidgen of number crunching, but pull up a chair; it'll be instructive, even fun.

In straight cost terms, the deals are actually close. Siebel has about $2 billion in cash on hand, so Oracle is really paying less than $4 billion. Meanwhile, eBay agreed to additional payments to Skype that could bring the total to about $4 billion, if certain performance measures are met.

Skype is projected to generate more than $200 million next year, a rather strong growth curve -- especially for a company that charges nothing for its primary product. Skype charges for people making calls outside its system, and for other services, but it's unclear how all that adds up in the long run. And while we don't know Skype's costs, we know it spends not one dime on marketing or other means to acquire customers. Nor does it have the infrastructure or maintenance costs that saddle traditional telecommunications carriers.

Siebel? Well, it generated $1.34 billion in revenue last year. But revenue has declined since 2002. Its profit last year was about $110 million, but it lost money in 2002 and 2003, and is swimming in red ink to the tune of $54 million so far this year.

Money to shop with before the deals? Oracle had a net of $461 million; eBay, a net of $3.6 billion.

Now I know what you're saying; you're saying okay, so maybe Oracle czar Larry Ellison is drinking even more dot-com bubbly than eBay CEO Meg Whitman. So what?

Well, the bubble was about companies with no earnings, just goofy notions scrawled on napkins. It was about stocks of companies going to the moon even though they had no real technology, just the promise of "eyeballs" that would visit their Web sites.

And it was about companies that kept throwing their IPO money at marketing and partying hearty and building sleek headquarters and fudging their numbers.

These recent deals? Well, Skype is the 54-million-customer gorilla in a business that Google and Microsoft and Yahoo all are scrambling to figure out. Skype is about to enter the large, untapped market of video conferencing. Its technology works, and it has strong partnership deals with real companies, such as Motorola for wireless compatible handsets.

In truth, eBay is partly responsible for all the naysaying.

The story it wants people to focus on is how Skype can be a whole new way for eBay buyers and sellers to communicate, thereby closing more deals more quickly, which means more money for eBay.

This does have the whiff of a dot-com convergence joke. But with eBay being the biggest Internet commerce success story in history, with profits from Day One and a tightknit community of 157 million users, it's a little hard to dismiss its instincts on these matters.

EBay can argue that it is now the leader in one of two primary ways people will communicate by voice: via their computers.

But this also carries the greatest risk for eBay. Skype is now in the spotlight, and competitors are gearing up.

One way some will fight back is by insisting that regulators apply all the obligations of wired phone carriers -- such as wiretapping access for law enforcement and 911 capability -- to Skype and services like it.

Many techno-geeks want Skype to open up its technology to conform to open standards, which Skype has resisted.

And it's never easy to go up against the likes of Microsoft and Google.

There's no doubt Skype represents a risk for eBay. But unlike many of the wild, open-ended risks of the bubble era, this one has some actual numbers behind it. Now it's up to the companies to prove they can make them add up.

Jonathan Krim can be reached at krimj@washpost.com.

Meg Whitman, CEO of eBay, which is getting into the Internet phone business with its Skype purchase.