| Item | Description | Last Updated |
| Carrier Systems | A list of carrier systems used on the Bell System. | July, 2003 |
| Telco CO Feature Codes | List of switch feature codes and their meanings. | January, 2002 |
| Item | Description | Last Updated |
| Carrier Systems | A list of carrier systems used on the Bell System. | July, 2003 |
| Telco CO Feature Codes | List of switch feature codes and their meanings. | January, 2002 |