Why can't my Nokia 6220C send SMS, but can I receive it?

There should be SMS settings in your information menu. Click in and there will be a mode setting. Click on it again and the mode 1, mode 2 and so on will appear. Click under the mode 1 and a dialog box will appear. One of the dialog boxes should have a telephone number, which contains the fixed telephone number of talents in your area. You can ask your friends around you to check the phone number in the way I gave you. You can confirm it in the dialog box. You may have accidentally deleted it. If it still doesn't work, you can only ask the staff of Nokia store ~