I have a Iphone 4 but I'm not sure wether its activated or locked how can I find out?

I have a Iphone 4 but I'm not sure wether its activated or locked how can I find out?
I bought a pay as you go micro sim from 3 but it doesn't seem to work as for the 24 hour wait
I've waited 3 days the sim still doesn't work so where is the problem is it the sim or the phone?

Added (1). Even if its a pay as you go sim I should still contact the Provider?

It's probably that the sim isn't activated, when I got my iPhone micro sim the sim wasn't activated I had to ring the service provider and ask them to activate it

Your sim probably is activated yet call the provider and tell them and do what they tell you to.

Yes. Even it's a pay as you go SIM, you still can contact your provider to activate the SIM card, or you can activate it through the service provider website.

If your SIM card is activate, but your phone still not working, it means your iPhone is locked. You can do the following steps to unlock it:

First of all, you have to jailbreak your phone using a program such as Redsnow or QuickPwn. This allows you to run applications on your iPhone that have not been approved by Apple. This is essential to unlocking your iPhone 4 because the applications (e.g. Cydia) used in the unlocking process are not Apple approved.

After that, you have to
- Go to "Settings" >> General
- Press on "Network" >> OFF "Enable 3G"
- Go to "Menu" >> Press the "Cydia" icon on your iPhone home screen.
- Press "Manage" when the app loads >> Source >> Press "Add"
- Enter in "repo666.ultrasn0w.com" (at Enter Cydia / APT URL) >> Add Source
- Go back to the Cydia sources menu and you will see the Ultrasnow package
- Click on it to download and wait as it is installed
- Turn off the iPhone.
- Use the paper clip to press the SIM tray release button on the top of the phone and remove the SIM card
- Place your new SIN card in the tray and close it
- Turn your phone on
- Your new network provider's details should appear on the screen.

If they do not, please check that the SIM card is correctly placed in the iPhone tray.

Your phone is now unlocked to any network.