This will guide you on how to add a single phone number to the SMS Opt Out list.
From the Admin dashboard, click on Call Center and then SMS Opt Out.
On the Manage SMS Opt Out page, click on Upload SMS Opt Out button.
Look for the Add a single Number section to add the phone number.
Enter the phone number under the phone number field. Choose Country and select the campaign where you want to assign the phone number.
In the example below, we entered 9149626823, country United States and campaign SMS Campaign. Click on Add button to add the phone number to the Opt Out list.
Once added, you will get a message that the phone number was added to the SMS Opt Out List.
You can verify it by searching the phone number under Manage SMS Opt Out page.