Did you happen to dial #01# during the process? If so, it adds the last caller to the list, which Im assuming is your Son's cell phone. Here are the full instructions. I will highlight what I think you should try.
Use Selective Call Rejection
Note: This feature is currently not working with Motorola SBV5222 modems. Please contact your local Cox center for assistance.
Selective Call Rejection allows you to program your phone to reject calls from any number you place in the rejection list.
When your service is turned on, any caller in this list will hear an announcement that you're not accepting calls at this time. All other calls will ring through as usual. To use this service, follow these steps:
Lift the handset and listen for the dial tone.
Press *60 (on a rotary phone, dial 1160).
Listen for an announcement telling you whether the feature is currently on or off. The recorded voice will then tell you how many (if any) numbers are currently stored in your rejection list.
Follow the voice instructions and press 3 to turn the feature on or off.
All steps complete.
To add the last caller to your rejection list:
Press #01# (on a rotary phone, dial 1201).
To hear the phone numbers on your list:
Press 1.
After the list is read, voice instructions will follow.
To add a number to your list:
Press # (on a rotary phone, dial 12).Follow the voice instructions you'll hear. You can store up to 31 phone numbers in your rejection list.
To remove a number from your list:
Press * (on a rotary phone, dial 11).
Follow the voice instructions to remove any or all of those numbers from your rejection list.
Notes:
To hear the instructions again press 0.
You will not be notified when or how many calls have been rejected.
Selective Call Rejection does not work if someone is calling from a blocked number.
You may press 1, 0, #, or * at any time rather than waiting for the voice instructions.
The list you create here is separate from any other lists you may be using for Priority Ringing, Call Waiting, Selective Call Acceptance, Selective Call Forwarding, and similar services.