A vertical service code (VSC) is a special code dialed prior to (or instead of) a telephone number that engages some type of special telephone service or feature. Typically preceded with an asterisk, or * (star), key on the touch tone keypad and colloquially referred to as star codes, most are two digits in length; as more services are developed, those that use 2 or 3 as the first digit are sometimes three digits in length. (from Wikipedia)
Verizon Calling Features Activation and Deactivation Codes
| Feature | Activate | Deactivate |
| *69 |    |
 |
| Anonymous Call Rejection |  |
|
| Busy Redial | |
|
| Call Block* |  |
|
| Call Forwarding |  |
 |
| Call Trace |  |
|
| Call Waiting/Cancel Call Waiting | Hookswitch | |
| Per Line Blocking |  |
|
| Per Call Blocking | |
Hang Up |
| Speed Dialing 8 |  |
|
| Speed Dialing 30 | |
|
| Three-Way Calling | Hookswitch |
* In some areas, press 3 to activate Call Block.
Rotary Instructions for Star Codes
Instructions for FiOS Digital Voice Calling Features
