Here are some options:
You can unlock your iPhone 3Gs anywhere if you have internet:)
No. You only need to unlock an iPhone if you want to use a different cell phone company with your iPhone.
The link below is the needed software to unlock the iPhone.
you can unlock any iphone or phone at unlock att .com i did my whole familys iphones there
To unlock iPhone 3gs on iOS 4.1 you have jailbreak your device first.
Depends on your software version if you even can unlock.
The Unlock codes for iPhone 4 to unlock the service network is usually provided by Vodafone who usually verify the information with Apple.
No, you can even unlock the iPhone when Jailbroken.
Yes
If you can't open your iPhone 5c because you forgot the passcode, maybe you can try MagFone iPhone Unlocker to unlock your device. You can easily unlock your iPhone within 4 steps. The first step is to connect your iPhone with the computer and open MagFone iPhone Unlocker, Then put your iPhone into DFU Mode or Recovery Mode, download and verify the Firmware Package. The last step is choose to Unlock your iPhone without Passcode.
How Do I get my wifi network back on my iphone
When you are at the lock screen, follow the "slide to unlock" message by sliding the screen to the right. Then input your passcode.