Blue Box - Special Codes

Special Codes

Some of the special codes a person could get onto are in the chart below. "NPA" is a U.S. telephone company term for 'area code'.

• NPA+100 – Plant Test – Balance termination
• NPA+101 – Plant Test – Toll Testing Board
• NPA+102 – Plant Test – Milliwatt tone (1004 Hz)
• NPA+103 – Plant Test – Signaling test termination
• NPA+104 – Plant Test – 2-way transmission and noise test
• NPA+105 – Plant Test – Automatic Transmission Measuring System
• NPA+106 – Plant Test – CCSA loop transmission test
• NPA+107 – Plant Test – Par meter generator
• NPA+108 – Plant Test – CCSA loop echo support maintenance
• NPA+109 – Plant Test – Echo canceler test line
• NPA+121 – Inward Operator
• NPA+131 – Operator Directory assistance
• NPA+141 – Rate and Route Information
• 914+151 – Overseas incoming (White Plains, NY)
• 212+151 – Overseas incoming (New York, NY)
• NPA+161 – trouble reporting operator (defunct)
• NPA+181 – Coin Refund Operator
• 914+182 – International Sender (White Plains, NY)
• 212+183 – International Sender (New York, NY)
• 412+184 – International Sender (Pittsburgh, PA)
• 407+185 – International Sender (Orlando, FL)
• 510+186 – International Sender (Oakland, CA)
• 303+187 – International Sender (Denver, CO)
• 212+188 – International Sender (New York, NY)

Not all NPAs had all functions.