If yes, why? And if No, why? Can anyone please explain a little?

What do you mean by Real Time OS? It doesn't store everything up and do it at 1am in the morning...

er, what? Could you explain what you're trying to find out??

Sorry people, if I was not clear. I mean is Symbian OS capable of handling I/O calls etc. as fast as a real time OS, like Win CE ? I mean when we are working with Win XP or Linux, we do not call it a real time OS, as they are too slow to be used to control a machine.

Symbian is a single user multi tasking style OS. As a single user, it is a real time OS. Unlike those multi user OS, it is a time sharing OS.

The currently released Symbian operating system versions do not have a real-time kernel & cannot be called a real-time OS.

As far as I know, neither has/can Windows CE.

That is, assuming that real-time means what it usually means - to my knowledge - in the context of operating systems; that interrupt processing is deterministic, predictable = you know the absolute maximum time (latency) for any interrupt generated for it to begin being processed.

Why do you ask? Is there a particular problem that you're trying to solve or are you just curious?