Galaxy S2 Skyrocket - can I update firmware w/ Cricket?

[Mark 42]

There is a new frimware update for my phone:

Which version of the Android™ platform does my Samsung Galaxy S® II Skyrocket™ use? : AT&T Cell Phones | Samsung

But it's from ATT.
We switched to Cricket as our new provider - can I still use the ATT firmware upgrade, or did Cricket install their own firmware when we switched?

It's possible Cricket already installed the newer version. How can I check I know it's somewhere in "About Device"
but not sure which part of the info would tell me)

All of the info appears to indicate I have that update:
Android version: 4.1.2
Baseband version: I727UCNJ1
Kernel version: 3.0.31-844945 se.infra@SWDA2502 #1 SMP PREEMPT Wed Oct 1 12:07:31 KST 2014
Build number: JZO54K.I727UCNJ1

But I think I saw an option to do an upgrade when I was in the menu where I go to delete the cache (by holding the power & both volume buttons during bootup)
(Obviously, I don't know a lot about smart phones).

 

[Rukbat]

There is a new frimware update for my phone:

Which version of the Android™ platform does my Samsung Galaxy S® II Skyrocket™ use? : AT&T Cell Phones | Samsung

But it's from ATT.
We switched to Cricket as our new provider - can I still use the ATT firmware upgrade, or did Cricket install their own firmware when we switched?

No, Cricket only "installed" a SIM card, you still have an AT&T phone as far as updates are concerned, but your phone has the latest update that's ever going to be written for it, so it's not going to be updated any further. If it would have been, you'd be on at least 4.3 by now (you're on 4.1.2), so you're never going to see KitKat or Lollipop for that phone. (That's the main reason carriers let you upgrade your phones every 18-24 months - the software outgrows the hardware in that amount of time, and you can't update the hardware [yet - Project Ara is working on phones that can have part swapped out, so you can add a faster CPU and more RAM to a phone and run later software on it].)

You've already had 3 major version updates (although Honeycomb was really supposed to be only for tablets) - most non-flagship [top of the line] phones are lucky to get one major version update and rarely get 2. Gingerbread is normally the last stop for phones made for it, because the jump to Ice Cream Sandwich needed so much more hardware.