According to naming, I thought that is the boosted version of T?

This post has been edited by kingkingyyk: Aug 30 2012, 08:56 AM

OTA = Other the air.
ICS does not come with OTA.
You need either Sony PC Companion or Update Service to do that.
Connect your phone to computer via USB.
For PC Companion :
1) Launch PC Companion, it will search for update automatically and notify you if new update is available.

For Update Service :
1) Launch Update Service.
2) Agree with the agreement.
3) Choose your phone.
4) Follow the on screen instruction.
5) It will provide 2 options if update is available, 1 is update, 1 is update + reset.

Expect your phone to run slower on ICS. Just root it (guide) after updating then you can start installing custom ICS ROM which is proven smoother than stock ICS ROM.