UPDATE!!! If you use iMessage, DON'T DO THIS

2014-09-03
warning-triangle-hi-1
iMessage stopped working on my iPhone after doing this. It still works on all of my other iDevices but not on my phone. I tried everything, clean restore etc, nothing worked. So please be aware, iMessage might stop working on your iPhone.

UPDATE 2!!!!######

2014-11-21

I CAN'T STRESS THIS ENOUGH, PLEASE TAKE NOTE OF YOUR ORIGINAL MAC ADDRESS BEFORE EVEN THINKING ABOUT TRYING THIS!

After restoring my phone I noticed that iMessages didn't work. It works on all of my other devices but not on my iPhone. I've tried everything, turned iMessage off on all devices, reactivating etc, nothing works. So if you want to use iMessage in the future; don't do this :)
It looks like I'm not alone: http://insanelyi.com/topic/18522-imessage-not-working-after-spoofing-mac-address-iphone-5/

Yesterday when I went by train I tried to spoof my (jailbroken) iPhone 5?s Mac address. Here in Sweden you get 400MB of free 4G surf when traveling with SJ, that's great! But, as you know, 400MB isn't really THAT much!

When you reach the limit you can still surf for free but with a reduced speed, nobody likes reduced speed.

I tried to clear my cookies, use another browser...nothing worked, my speed was still reduced. I couldn't stand it.
Soooo,I decided to spoof my MAC-address. Yes I know what you're thinking, pretty dumb idea, but what could POSSIBLY go wrong?!

I fired up MobileTerminal and run ifconfig and printscreened the shit out of my current MAC-address(yes im not THAT stupid)!
Then I ran the following command:(and YES im perfectly aware what NV in nvram means: NON VOLATILE, aka it will keep it's memory even when the iPhone reboots/shutsdown):

nvram wifiaddr='XX:XX:XX:XX:XX:XX'

You can read more about nvram here

BAM!
I ran ifconfig once again and yes, my MAC-address had changed, GREAT SUCCESS!
I then reconnected to the free WIFI and YES, my speed wasn't reduced anymore.
I did this 3 times during my 2h journey and it worked everytime.

This post could've ended here.
However...

I thought it was too easy. I thought about the NV again...
I decided to reboot my phone. Say hello to ACTIVATION SCREEN OF DEATH.

I needed to activate my iPhone again using iTunes. No big deal.
But after activating my phone was fucked. It displayed 0k in iTunes and no apps were showing. I could still use my phone except for the WIFI, it was just greyed out.

So I choosed to restore my phone. After restoring and setting everything up, I noticed that the WIFI icon WAS STILL GREYED OUT...remember the NV part in NVRAM? Fuck.

When the phone got restored it also got updated to 7.1.2, luckily for me it can be jailbroken. So i jailbroke it once again with Pangu, installed MobileTerminal...

Ran this little magic command:
nvram -d wifiaddr and rebooted my phone.
I needed to reactivate my phone once again but after that, the WIFI WORKED.

If 7.1.2 was "un-jailbreakable" I would have been...screwed.

So, was it worth all the trouble? Totally.