James Martin/CNET

And so the rumor resurfaces like a vole from a hole.

Facebook is, apparently, building a phone.

Naturally, details are scarce. However, the reason(s) why Facebook might want to do this are not. The company needs to make more money. There you have it.

Some speculate that Facebook will scrabble around in the lower-end of the market with Google. Others speculate that the heart of this alleged new mobile device will be a camera.

But let's look at it from the human being's point of view. What could Facebook place before your eyes that would make you come over with such deep desire that you wouldn't be able to resist?

The first, and perhaps most obvious thing, would be that the company would give this phone away. Yes, for free. It would say: "Hey, we're always been a fabulously free service. So here's a fabulously free phone. There's just one catch: you have to watch some ads before you use it. Oh, and listen to some ads while you use it."

Does that make you salivate?

Well, judging by the apparent performance of ads on Facebook, the whole ad thing might not be working out as well as was hoped. Indeed, last week Facebook's COO, Sheryl Sandberg, gave a speech at Harvard in which she jokingly (or not) begged the audience to click on a few more ads.

In any case, don't people ignore mobile ads even more than they ignore Facebook ads?

So let's assume, then, that Facebook will want to charge you for this phone. Presumably, then, it will be competing against every other phone in the market. You know, the Galaxy S II, the Nexus, and that iPhone thing that some people seem to like.

What might be the obstacles here? It seems to me there would be one rather vast one: Facebook has never sold anything. It's not so much that Facebook has never been in the hardware business. It's never been in the selling business.

It is slightly similar to the problem Google had when it started selling phones the first time around. It seemed as if the company believed people would rush to buy something they hadn't even touched, just because Google had made it.

In Facebook's case, I would be surprised if there were too many human beings for whom the essential idea of a phone made by Facebook is terribly exciting. The Facebook brand isn't that strong. It's more of a utility. It isn't the sort of brand where acolytes cannot wait for the next thing to come out of Facebook.

Perhaps, then, Facebook will partner with someone to market its product. But what would be the ultimate purpose of the phone -- other than the obvious one of trying to make some money out of its users?

The New York Times, which began this current suggestion, says that Mark Zuckerberg is scared that Facebook "will simply become an app on other mobile platforms."

Which suggests that the company really, really wants to own your mobile Facebook experience in a way in which no one else can benefit.

How about creating your own exclusive mobile Facebook ecosystem? Yes, here's something that would surely excite all of those for whom a day without Facebook is a day without love: a phone that gives you exclusive Facebook performance -- however, you decide to define that word.

In fact, wouldn't the most attractive idea for a Facebook phone be this: The new HTC Facebooker. The only phone with which you can actually log on to Facebook?