After a several times of using *#7370# I succeeded it. OK, to make long story short: every time when QT installing was started, PIPS-installer returned with a strange error and installation was ended by phone. What I've done: installing CODA for Symbian^1, rebooting, installing qt for Symbian^1 aaaand... getting the error and trying once again.

So I don't know even where was problem...

What is the installed Qt version on the phone?

Have you tried to download and install any Qt apps/games from the Nokia/OVI Store?

Have you tried unistalling and reistalling the Qt from the phone?

(Don't doubt there are couple of hundred million symbian users waiting for new apps/games:))

Unfortunately, I tried to make it work last two days, but still, QT Creator can't recognize QT version on that phone. I got a bit stuck there... And the main clue, what I got from my phone:
"this software and phone aren't compatible"(About Symbian^1 stuff). At this moment, I highly doubt, that such operating system as Symbian is a good environment for developing..............