Dial (or 1160 on rotary/pulse phones) to call into the automated Selective Call Rejection system.
He took a deep breath. He remembered a golden rule of I.T. troubleshooting from his school's tech support guy: If you don't know the code, look for the physicality of the object. how do you unblock a phone number on a landline better
Lift your landline handset and listen for a standard dial tone. Dial (or 1160 on rotary/pulse phones) to call