While talking on call...

[dude1]

It happened 5 times already.

So I take a call, all good, I'm on headphones cause I like my hands free and suddenly the other's person voice is heard only through the back speaker, if I say smth, he cannot hear me and it enters in a "stand by" mode where a XPERIA screen appears. After 15-30 seconds, it comes back to normal.

Why is this happening?

[Alexander1]

Seems pretty strange. Try to start your phone in safe mode to see if any 3rd party app you have installed might cause the problem. Check the safe mode FAQ topic for more info: 

http://talk.sonymobile.com/t5/FAQ/How-to-boot-your-phone-into-safe-mode/m-p/348008#U348008

If the problem persists in safe mode I suggest that you repair the phone software using PC Companion:

http://www.sonymobile.com/update

[dude1]

The thing is that it doesn't happen everytime. Once in a while, you know. For example, it happened twice in the last two days.

Should I skip to PC Companion directly or start my phone in safe mode and hope it happens again?

Glad I remembered this forum

[dude1]

I've noticed something else: the clock was wrong and it entered that state again. When it recovered, the clock showed the exact time. And the red signal is on, even though is almost fully charged.

[saripoiu]

and me too

[saripoiu]

and me too

why do not you simple software without facebook, google+, talk, etc.. background eating resources and who needs to put them up later after his main phone function is not leptop. please if you can make me I do not matter what software version

[jpraveenanand]

It happened for me too 3-4 times in last 5 2 months...sony, kindly provided a stable update for this device

[Alexander1]

Have you really tried to boot the phone in safe mode? Do you experience the same behavior even in safe mode? 

[saripoiu]

the same in safe mode
best simple software

[Alexander1]

In that case, perhaps you should have your phone examined by a service center. Please contact your local Xperia support team for more information: 

http://www.sonymobile.com/global-en/support/contact-us/