solution to "activation error" on iphone 4

Hello activation__error,

Thank you for posting in Apple Support Communities. It seems you are having problems activating your iPhone.

You'll want to follow these steps, If you can't activate your iPhone

"If you can't activate your iPhone

If your iPhone can't be activated or an alert says the activation server is unavailable or the SIM card is unsupported, learn what to do.

Before you begin

• If you get an error message that says "No SIM" or "Invalid SIM," learn what to do.
• Check the list on the System Status page. If the box by iOS Device Activation isn't green, try to activate your iPhone later.
• If asked to enter your password as you activate your iPhone, enter the password. (A password prompt means that Activation Lock might be enabled in Find My iPhone.)

Still need help? Use the next section.

Follow these steps

1. Restart your iPhone.
2. If you're using a cellular-data connection, connect to a reliable Wi-Fi network instead.
3. If you get an error message on your iPhone that says the activation server is temporarily unavailable or cannot be reached when trying to activate, wait a few minutes, then repeat the previous steps.

If you still can't activate your iPhone, try again using your computer instead. Here's how:

1. Make sure that you have the latest version of macOS or the latest version of iTunes.
2. Check that your computer has an Internet connection.
3. With the cable that came with your iPhone, connect your iPhone to your computer. Locate your device on your computer.
4. Wait while your computer detects and activates your iPhone: 

• If you see an alert that shows "Set up as New" or "Restore from Backup," it means your iPhone is activated.
• If you get an error message on your computer that says that the SIM card isn't compatible or is invalid, contact your carrier.
• If you get an error message that says the "activation information was invalid" or "activation information could not be obtained from the device," use recovery mode to restore your iPhone.

If you still can't activate your iPhone, contact Apple Support."

Cheers!

See -> If you can't activate your iPhone or iPad (Wi-Fi + Cellular)

If you can't activate your iPhone or iPad (Wi-Fi + Cellular) - Apple Support

-> If you still can't activate your iPhone or iPad, contact Apple Support.