"You promised, Daddy," runs the living room lament as this unwitting foreigner brings up the subject. "You promised, everyone at school has one." On closer interrogation that proves an exaggeration - the true proportion is about one in three but, in a sense, Consta and Selma are right. Statistics show that pretty soon there'll be as many mobiles (some five million) as there are Finns.
And that's only the half of it. For Finns are into mobile phones with the same zeal they once reserved for saving their country from the Swedes and Russians.
The gadget has transformed the national image, too. Weren't the Finns supposed to be a taciturn, vodka-sodden bunch, speaking an impenetrable language, producing lots of fish and timber, but mainly notable for winning the Monte Carlo rally each and every year?
Breathe the word Finland to the technologically enlightened these days, and their eyes mist over at the thought of sleek little mobiles that can practically think, and a million twinkling internet screens lighting up the Arctic night.
Not surprisingly Nokia, the Finnish company that has just overtaken Motorola to become the world's biggest manufacturer of mobile phones, has become as virile a symbol of national pride as the Winter War against the Russians almost 60 years ago.
Speak the words "mobile phone" to a Finn, and a broad, slow smile will spread across his face, as if to say, "You didn't think we were up to that sort of thing, did you?"
Nokia is Finland's General Motors; As with GM and America, what's good for one is good for the other. The company generates, on its own, a third of Finland's annual economic growth; its shares account for half the trading on the Helsinki stock exchange and Jorma Ollila, Nokia's president, was recently voted the second most powerful person in the country; it was probably only the Finns' respect for democracy that kept the Prime Minister at number one. Which is fine, but God help Finland if the mobile phone market ever takes a plunge.
Why should the cutting edge of IT have descended among these dark northern forests in the first place? Some say it is precisely because of this wilderness that Finns have more mobile phones, and more internet users, per head than any country in the world. How else are they to keep in touch across their vast, underpopulated land?
In fact, the phone gives the lie to the Finns' view of themselves. They do like to talk, but not face-to-face.
Thus the peculiar world of the Helsinki bus, of citizens who would not dream of passing the time of day with the person in the next seat, but whose reveries are constantly disturbed by a carillon of mobiles ringing around them.
And there is a more prosaic consideration. Phones are attractive, aggressively marketed (of this year's Christmas advertisements in Finnish papers and on TV, at least half seem to be for mobiles) and transparently priced.
Unlike Britain, where the unit is cheap and the costs, if you're not careful, can be crippling, you know what you're getting in Finland. You pay up front - sometimes pounds 100 or more - for the "terminal," as the companies like to call it, but barely above fixed line rates per unit.
Even so, how do you sell more phones in a country where everyone already has one? Children of course are part of the answer. You give them "Citiphones" which won't work outside the Helsinki area and which cut off after, say, 100 markka (pounds 12). More importantly, you persuade people they need not one but several mobiles.
A top executive of Sonera, the Finnish equivalent of BT, expounded the doctrine to me thus: "People want to work in a flexible way. That means one mobile like a palm-sized laptop, hooked up to webservers and so on. Then a car-phone, then a smart phone for handling e-mail and the rest and finally a small handy one for weekends."
The mobile, in short, is Finland's entrant in the race for the electronic future, where the telephone, the computer and the television are fused into one. In 2004, the Sonera man told me, the third generation of mobiles would be launched, with full video services. Already, open-out mobiles that offer a keyboard and connection to the Internet are widespread. Consta and Selma of course won't be getting one of those.
But next year, if not this, Santa will surely have a mobile for them in his sack.