iPhone 5, iOS 7.0.4, Erased with Find my iPhone, will not re-activate

First of all:

1. I have no firewall or anti-virus software blocking ANY outgoing connection
2. my iPhone is not jailbroken
3. I have never used my MacBook Pro to jailbreak another device
4. there is no gs.apple.com entry in my hosts file
5. I have tried to re-activate the phone from three different wireless and wired Internet connections
6. I have tried to re-activate the phone from my own iTunes which as been synced to the iPhone hundreds of times

Here's what happened:

1. I left my phone in a taxi three nights ago
2. I went on to Find my iPhone and locked and erased the phone
3. I received a call a few minutes later and the iphone was returned to me within an hour

After three days I have been unable to re-activate my phone.

1. I have tried three Apple-based high-speed networks
2. I have powered the phone on and off over and over
3. I have held down the home and power button to re-reset the phone
4. I have treid the in-phone activation more than 100 times and the same thing always happens
   1. If I use the iPhone connected to wireless, the iPhone says, "Your iPhone could not be activated because the activation server is temporarily unavailable. Try connecting your iPhone to iTunes to activate it, or try again in a couple of minutes.
   2. If I try to activate with iTunes I get the following message from iTunes, The SIM card inserted in this iPhone is PIN locked. Please enter the PIN code of your SIM card and connect your iPhone to iTunes again.

The phone is not asking me to unlock the SIM, I know the code for the SIM but the iPhone doesn't ask for it. The iPhone doesn't ask for me to log in to my iCloud account with my iCloud details, which I also have.

Surely the point of "Find my iPhone" is that once one gets the iPhone back one is able to somehow use the phone again.

Can anyone shed any light on why I can't re-activate my own phone?