I have I337M that is running 4.2.2. Would like to update to 4.3 or higher but my carrier Alaska Communications (ACS) has not provided any updates. Looking for simple (relatively) ways to upgrade the firmware. ACS is very small and I can find very little info about upgrading firmware. It seems like my I337M is essentially a Canadian phone but I am not sure if I use any of the Canadian specific firmwares if I will be able to make calls. I do not have ready access to a PC, only Mac. Looked into the CM Mac installer but still nervous. Any ideas appreciated.