We'd love to help you with this! Depending on your device, there may be a built-in feature which allows you to block numbers. If you aren't sure, you can check the Device Support page to double check. Once you select your device, search for "block" in the search tab. If results relating to "block calls" appears, you are able to do so through your device.
If you don't have the feature, you can look into our Call Protect feature. This essentially allows you to create your own block list, as well as other features. Let us know if you have any further questions about blocking unwanted calls.
Collin, AT&T Community Specialist
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