I recently got a Lumia 521 from Newegg for a pretty good price. One of the reasons I got it was because it has Wifi calling. I got the phone but didn't see a Wifi calling setting in the options. I also tried setting up a Google account because all my contacts were in Google, but WP8 could not sync with that account because Google removed Exchange Activesync support for users who were not using EAS before Dec 31, 2013. The Windows Phone support site said that a new software update should fix that problem.
I tried downloading the update but it kept erroring out. I also called customer support about it and they walked me through a few things, but everytime I tried updating, it kept erroring out. I tried 4 different Wifi access points (thinking it may be a problem with the old router I used) and still no luck.
Here are some of the problems that I encountered and how I got around them:
1. Windows phone update will not work if the time on the device is in the past. For some reason, if the phone boots up without a SIM card, the date defaults to August 31, 2012. If you try to update the software, it just errors out with a cryptic error code. Of course, it doesn't tell you to fix the time (or better yet, figure out the darn time on its own). Update the time manually, and that error goes away. I forgot the ID for this type of error. I googled the error code and got some info about windows vista and windows 7 (looks like they use the same error codes). I updated the time manually to the current time, and that error went away.
2. After the time was corrected manually (I also tried putting in my SIM card after a bunch of retries), it'd show "checking for updates"... for a looong time then start the progress bar for a bit. Then it'd error out with error 801881d0. A google search brings up a page which says it may be because of an unstable internet connection, but I tried 4 different APs, within 3-4 feet of a strong signal and it still errored out. I wasted about 5 hours trying different things and got incredibly frustrated. I tried with and without SIM, different routers, changed the channels and AP names on the router, with and without SD card and everything else I could think of.
This morning, a friend pointed me to this tool: FAQ - FAQ - How can I recover/reset/restore my phone software? - Nokia - UK.
I downloaded the program, installed it on a Windows 7 machine (it took a while), hooked up my phone, and it detected it immediately and informed me that an update is available. My phone came with 1030.6409.1311.0011 and the tool upgraded it to 3056.40000.1404.0034. The tmobile support page here Software version: Nokia Lumia 521 | T-Mobile Support says that the second set of digits is 0000, but the Nokia tool (and my phone) says that it's 40000. After the update, my google account syncs fine and I have all my contacts although it's set up as IMAP and does not have push email. I also see the Wifi calling option now. It was a 1.35GB download for the update and it erased all my data.
I searched a lot to find if there was a computer-based way of updating this phone and I did not get good first impression about WP8. I love the smooth and fluid UI, and the live tiles. They have to work on the user friendliness a bit, and solve these cryptic errors. Not giving an option to update over a computer when all else fails is not a good thing. Windows phone support site says nothing about this Nokia tool.
I think the problem may be with the server that does the OTA update. Something is causing it to error out after a while. I'm so glad my friend sent me information about this tool; that phone would have been on its way back if not for that tool. I hope this helps someone else in the same situation.
EDIT: I tried to find an option to download the update over cellular data, but I couldn't. The phone forces you to be on wifi to download the update and waits for wifi if you're on mobile data. I checked with customer support, and they weren't able to find where to change this either. I'm not sure if this is a T-mobile restriction or a WP8 restriction.