If a legitimate caller tells you they cannot get through and they hear a message saying you do not accept blocked calls, you need to turn this feature off.
Most traditional landlines use "star codes" to manage network-level features. If you blocked a number using your service provider's system, these are the fastest ways to undo it.
First, determine which scenario applies to you:
Sometimes, the issue isn't that someone is blocked from calling you, but that you have blocked your own number from appearing on someone else's phone (Outgoing Caller ID blocking). If your calls aren't going through because the recipient blocks unknown numbers, you need to unblock your ID for that specific call.