If you blocked a number through your carrier’s “Smart Block” or “Call Filter” app:

To unblock a phone number, the steps vary depending on your phone's operating system and the specific method you used to block the number. Here are general steps for both Android and iOS devices:

For traditional landline services, you can often manage blocks using touch-tone codes. How to Unblock a Phone Number on Android | Expert Q&A

Long-press the blocked number (often marked with a slashed circle icon). Tap and confirm. On iPhone (iOS)