Firefox and Inkscape have network effects, albeit more limited than Skype. The more people using Firefox, the more sites work with Firefox. Not a big issue now, but it was. And Firefox must have spread largely through word of mouth (actually anyone done research on how Firefox adoption did predominantly occur?). More people using Inkscape, more acceptable it is to use, and better it works with files one might receive (assuming Inkscape works a bit better with svg than with Illustrator or whatever that it must import), same for Open/LibreOffice (which definitely works better with ODF than OOXML). All software has network effects to some extent; a significant reason why using free/open source software is a matter of good citizenship, not just getting stuff done.

"I think that communication is a winner takes all"

Which cell phone manufacturer has "taken all"?

You seem to be basing your statement on the impossibility of interoperability, which is an odd position to take, at least if you actually think about it.

Regarding cell phone manufacturers: that's not really the same thing.

Phone numbers are universal. It's not like an iPhone user on AT&T can only call other AT&T users[1], or that T-Mobile customers can only call other T-Mobile customers. Skype limits me to reaching out to other Skype users. FaceTime only works with people who have bought into the Apple ecosystem.

[1] Although one might suggest that these iPhone users can, in fact, call no one.

Well, that's due to rigorous standardization. Think about the speech codecs etc. used in mobile telephony. It's not like a phone number gives you anything more than an IP address does.

Ah, you got my point.

Actually, browsers do have network effects. If you're not important enough that web developers test their sites against you, you are going to suffer. See Opera.

skype alternatives do have a (small) chance despite strong network effects.

1/ policy makers do not like running a third-party closed-source obfuscated binary with undefined behavior aggressively evading firewalls inside their business or country (in the case of China).

2/ the network effects are not nearly as strong as, for instance, ebay's. i do not care about being able to call random strangers on skype, only about my contacts. the scope of the network effect is to some extent that of a social group, not an entire market.

The network effects are (luckily) also not exclusive. There's no reason why you can't use Skype AND a SIP phone AND GNU phone software - the only time it's an issue is when you want to do a conference call. That said, if GNU want to win this one, they'd better not make freedom their main "selling" point. Skype's usability and reliability leave some room for improvement, and users might care about those points enough to switch.

Actually in this case they can win on freedom and they can do so by telling people that anybody can listen to their phonecalls (which is very likely true, almost certainly with a warrant) -- people care about their privacy (even though most likely nobody cares what they are saying).

But more importantly Skype can fix the ux. They cannot fix the freedom issue (and if they somehow manage to do so anyway, great).

>only about my contacts

So Alice has to install Google talk to call you, skype to call Bob and SIP to talk to Carol

Meanwhile Bob has microsoft phone to talk to ....