If you mean voice calls then I disagree. They seem to becoming less important every year.

What percentage of people worldwide use smartphones with no voice service at all? Including voip.

That's beside the point. You can have voice calls and choose not to use them very often.

I'm talking about actual usage. My personal observation is that usage of voice calls is declining - especially among the young.

You still want a way to make voice calls in case you need to contact emergency services, no?

At no point did I say "nobody ever makes voice calls any more".

The point being the option to call emergency services still makes phone software the killer app for smartphones.

"Calling emergency services is the killer app for phones" - yes.

"Calling emergency services is the killer app for smartphones" - no. "Killer app " implies that this is the reason people buy them. If this statement was true then people would buy cheap feature phones.

It's worth repeating the original statement here:

> smartphones didn't have "a" killer app per sè I don't think, but they became part of everyone's daily lives in a really short timeframe. [...]

to which alach11 replied:

> The killer app for smartphones is being a phone.

True. The Iphone is an Ipod Touch with a sim card.

The iPhone predates the iPod Touch.

I know, but not by much, they were both announced in 2007.

that wasn't the reason to get a smartphone over a phone. First killer app was email