ResolutionIn contrast to most of my posts, the solution to this is actually available pretty readily on the internet . I am posting this to confirm that it worked on my two phones, because people are pretty bad at updating forum posts once they've found a solution.
The fix in this case is to run a firmware update via the "Samsung Kies" software. This firmware update is not available OTA. Testing over a ~24 hour period I have been unable to reproduce the problem, which was quite easily reproduced before the update.
While researching this problem, I found many similar reports of other Galaxy phones (s3,s4,etc) having the same problem. None of those reports seemed to have a resolution, only the Galaxy Light thread had anyone confirm that they had fixed it. So, if you have another Galaxy phone with the same problem, I would check to see if there is a firmware update available via the Kies software.
Installing and running Kies software
- Download the Kies software for your platform from Samsung's website
- There are two versions "Kies" and "Kies 3". For the Galaxy Light, you want "Kies", newer phones may need the "Kies 3"
- There is also a version for Mac, only one version though, not sure if that works for all phones or what.
- Install the Kies software.
- There isn't much to do here. Just click next a whole bunch really. Though I did opt to install the "universal drier tool", not sure if that's necessary.
- Open the Kies software, you should see a "connect your device" type prompt. Connect your device.
- If this is the first time you've plugged in your phone to the computer it may take a few minutes to install drivers.
- Note: I did have one of my phones lock up while connecting it to the computer (screen and hardware buttons became unresponsive). A Force reboot fixed it.
- The device needs to be in MTP mode, not PTP mode. Kies will warn you if it's not.
- When I hooked up my phones, it immediately prompted me to do the firmware upgrade. If this doesn't happen for you, the "Basic Information" tab should show the current firmware and whether or not it's up to date.
- Follow Kies instructions to upgrade the firmware.
- The first time I ran this, I let the phone go to sleep while Kies downloaded the firmware update. Since the download took a while (I don't have super fast internet at home) the phone disconnected from Kies and I had to start the process all over again. Had to sit there swiping the screen back and forth while the download happened to keep it from sleeping/disconnecting.
- Phone will reboot and install, don't turn it off or do anything to it while this happens.
- The upgrade performed just fine for me on both phones, with no loss of data. Still, if you have critical stuff on your phone (why do you have critical stuff on your phone?, keep that stuff somewhere less steal-able) maybe back up the phone (can be done with Kies (Backup/Restore tab), or about 1000 other things) before doing the upgrade, just in case.
In interest of full documentation, One call I made right after the upgrade had really poor call quality (sounded like I was underwater). This was one call and have not had the problem reoccur since.
The Problem / Full StoryWe recently switched to T-mobile because they're reasonably cheap (for what you get) and their business model is slightly less troublesome than most big carriers. <Rant>took about 8 hours on the phone over 2 days to get the plan set up properly because the original guy who sold us the plan didn't know what he was doing </Rant> . Anyway we brought our devices, because you can pick up the Galaxy Light on Amazon for dirt cheap. It's not a high-end phone, but it's a reasonable spec with a fairly recent version of android (4.2.2).
But enough advertising, you wouldn't be here if you weren't having a problem. The phones worked fine for a few days, but we started having problems with the WiFi calling within about a week. WiFi calling was a big deal for us because all carriers (besides Verizon, but fuck them) have not-so-great coverage in my town, but we have WiFi pretty much everywhere we go. So problems with the WiFi calling was problems with our service in general.
Problems were as follows. If the phone was allowed to sleep for awhile (seemed to be 30-45 minutes on average) WiFi calling would stop working. This means, with out a cell signal (which I don't get at work because my building is made out of concrete and florescent lighting) no calls could be made or received and no texts could be sent or received. Not that the phone was aware of this, the WiFi calling icon in the notification bar was still blue and it said it was making calls over WiFi. When you actually tried to place a call, however, it would immediately end the call (at 0:00 seconds) and call status would be "Call Ended". Looking at call history you would see "Canceled". Trying to send Texts would result in a "Failed to Send" message. People trying to call us would get send straight to voicemail, or occasionally one ring then voicemail. Then only way to restore service was to turn WiFi calling off-and-on (usually) or reboot the phone. This fix would only last until the phone went into some low sleep state (seemed to be ~30 min of screen off).
After much internet searching and playing around with settings on the phone I came across this thread (also linked at top) about the WiFi calling on the Galaxy Light. A non-OTA firmware upgrade was available and fixed the problem (see above for steps).
Here's some things I tried that did not work
- Clearing data (via application manager) from "WfcService" and "Wi-Fi Calling Settings"
- Changing Wi-Fi calling preferences (prefer cell, etc.)
- Different Wi-Fi networks
- Standing close to router (router is on my desk at home, so while sitting at desk phone is <5 feet from router)
- Turning off voice control
- Turning off other wireless radios (bluetooth, gps, NFC, etc.)
- New phone - This appears to be a problem with at least all Galaxy phones. Seen reports of people getting phones replaced 4 or more times without resolution.
- Factory Reset
- Changing network mode (LTE/WCDMA/GSM, WCDMA/GSM, WCDMA only, GSM only)
- Changing Sim cards/upgrading sim cards
- opening ports on router