I'd be more than happy to assist you! Hope all is well on your end. Unfortunately it varies from carrier to carrier, and sometimes phone to phone. So I can provide you with a comprehensive answer, please provide the model of your cell phone.
See if one of these options works for your phone model.
Scroll to and select the option for your phone book.
Press the "Menu" button when your list opens up.
Select the "Block List" option.
Press the "OK" selection to add numbers to your block list. Follow the portions below for the specific type of number you want to block.
Select the option for "Number" or "Unknown Numbers" from the block list.
Type in the number that you want to block or select the option to block all unknown callers (calls with no caller ID).
Select the "Save" option.
Select the option for "Contacts" or "Recent Contacts" from the block list.
Scroll to and select the desired contact that appears.
Press the "OK" button to confirm.
Select the option to "Save."
Select "Menu" from your phone.
Select the "Phone Book" option from the menu.
Select the option "New Entry"/ "New Contact." Options vary depending on the phone model. Enter the contact number and name of the person you want to block and click "Save" to add this person in your contacts list.
Go back to the "Menu" screen of your phone. Select "Contacts" and select "Group." Press the "OK" button. The contacts list is shown; add the new contact entry you want to block into this group. The contact will be added to the new group.
Select "Settings"/"Tools" from the "Menu" screen of the phone. Now select "Security." You may then be asked to enter your phone's lock code. The default code of your phone is the last 4 digits of your phone number.
Select "Restriction"/"Blocking" after entering the code. You will see three options now, "Outgoing", "Incoming", "Contacts." Select the option "Contacts" and choose the group that contains the specific number to be blocked. Press the "OK" button to enable the selected Restriction. You will no longer receive calls or texts from this number.