What we've not seen though is an explicit defensive phaser fire against incoming photon torpedoes.
...Although Kirk apparently called for that very thing in ST2, against Khan's last torpedo in the first fight.
Wasn't there an episode where they fired photon torpedoes into a star and the casings protected the warhead up till when it was needed to explode?
"Quality of Life". And apparently Soran's starkiller missile had some of those qualities as well. Then again, starships can fly into stars and survive for certain lengths of time, yet weapons exist to pierce their defenses.
Kelvin poured phaser fire into the Narada for a good twenty minutes
It seemed every shot was fired defensively, at the incoming missiles. Of course, any miss would head in the general direction of the Narada
. But then again, the enemy ship was "porous" and in theory the misses might have passed between her tentacles.
There are a couple of good arguments for saying that the shields of STXI are not forcefields, at least not of the usual Trek sort. Namely, they never
a) flare up visually at impact
b) visibly protect from kinetic impact, be it at high or low speed, a weapons hit or a bump, or
c) prevent transporting.
On the other hand, the largest shuttle type is said to have shielding, yet is very unlikely to feature CIWS cannon in any of its incarnations. Robau twice orders power to shields, first when weapons are said to be offline, and next when no fighting is going on, in both cases suggesting that the weapons are not the shields (and never mind the separate terminology!). Pike in turn orders shields up when arriving at Vulcan but never gets any CIWS results of any sort out of it. Nero's first hit reduces shields but involves no CIWS activity. And Pike's officer refers to "deflector shields" as the thing that was tested by Sulu's bumping into jetsam - interestingly, the thing that failed to prevent scraping and physical damage despite "holding". All in all, then, CIWS is unlikely to be the same as shields in that universe, and it remains debatable if a separate CIWS system even exists; possibly it is just a mode for operating the generic (if two-tier) weaponry of the Kelvin