Here is the list of "Star Codes". I do not mean for it to be exhaustive.

These codes work in the US and I believe Canada. These services are only available to land-line or cellular telephones. Some require additional services be purchased from the telephone company to use them.

*40 - Change Forward-To Number :followed by directory number is used to change the forwarded-to number for Call Forwarding when line is busy.

*42- Change Forward-To Number: followed by directory number is used to change the forwarded-to number for Call Forwarding when phone not answered.

*44 - Voice Activated Dialing - Customers will dial this code to access their VAD directory in order to add, delete or review the names and numbers

*45 - Extended Dial Tone - Customers will dial this code to extend the length of time in which dial tone is heard after going off-hook so that various equipment (i.e., fax and modems) will work properly.

*46 - French Voice Activated Network Control - The caller can say a name or command in French that will be activated, deactivated or provide access to a service, e.g., Call Forwarding, Call Trace, etc.

*47 - Allows you to override restricted 1+ calls from that line. Dial a PIN and then a 1+ call after receiving a second dial tone.

*48 - Override Do Not Disturb - then dial a Personal Identification Number (PIN) thus allowing the call to be completed in the normal manner.

*49 - Long Distance Signal - Extended period activation/deactivation (toggle) of basic 1FR/1MR long distance signal ringing/call waiting tones.

*50 - Voice Activated Network Control - You can say a name or command that will be activated, deactivated or to access a service.

*51 - Who Called Me? - Provides the directory number (DN), date, and time of unanswered calls.

*52 - Call Hold - (Single Line)You can place a call on hold so that the call may be continued from another extension.

*53 - Distinctive Ring B - You can select, by way of distinctive ringing, the particular person or extension that the you wish to alert.

*54 - Distinctive Ring C - :(same as *53).

*55 - Distinctive Ring D - :(same as *53).

*56 - Change Forward-To Number - followed by directory number (DN) is used to change the Forward-To number for Call Forwarding Variable feature button.

*57 - Customer Originated Trace - Provides the recipient of an obscene, harassing, or threatening call the ability to request an auto-trace of the last call received.

*58 Activation, *59 Deactivation - Allows you to inhibit other stations from picking up a call on hold or bridging onto a call that is active at the station.

*60 Activation, *80 Deactivation - Selective Call Rejection - Allows you to have incoming calls from a limited number of calling parties rejected by the terminating switching system.

*61 Activation, *81 Deactivation - Distinctive Ringing/Call Waiting - Allows you to have incoming calls from a limited number of calling parties identified using distinctive alerting treatment.

*62 - Selective Call Waiting - Provides you with the ability to provide a Call Waiting signal to a predetermined list of directory numbers specified by you. Callers not on the predetermined list will receive busy tone.

*63 Activation, *83 Deactivation - Selective Call Forwarding - Allows you to have incoming calls from a limited number of calling parties
forwarded to a pre-specified remote station.

*64 Activation, *84 Deactivation - Selective Call Acceptance - Gives you the ability to block calls from all but a predetermined list of directory numbers you specified. Unaccepted callers may receive an announcement or be routed to a predetermined directory number.

*65 Activation, *85 Deactivation - Calling Number Delivery - It gives you the directory number (DN) of the calling party during the ringing cycle.

*66 Activation, *86 Deactivation - Automatic Callback - or Redial

*67 - Known as per-phone call Caller ID Blocking

*68 Activation, *88 Deactivation - Call Forwarding Busy Line/Don't Answer -

*69 Activation, *89 Deactivation - Automatic Recall

*70 - Cancel Call Waiting -

*71 - Usage Sensitive Three-way Calling - Add a third party to the two-way connection that is established by subsequent dialing.

*72 Activation, *73 Deactivation - Call Forwarding

*74 Speed Calling 8-Change List - See *75

*75 Speed Calling 30-Change List - Speed Calling - Allows you to assign your own speed calling codes directly and immediately from your own telephone by dialing a change speed calling list access code, an abbreviated code, and a new telephone number.

*76 - Advanced Call Waiting Deluxe - You can specify, in advance of incoming calls, the termination treatment on incoming calls that arrive while the you are engaged in another conversation.

*77 Activation, *87 Deactivation - Anonymous Call Rejection - (Note to cell phone users: *77 on some cell phone networks in some locations is reserved for State Police, as it has the alphabetical equivalent of "*SP".)

*78 Activation, *79 Deactivation - Do Not Disturb - The calling party will receive a message indicating the station is in Do Not Disturb condition.

*82 - Line Blocking Deactivation

*90 Activation, *91 Deactivation - Customer Programmable Call Forwarding Busy Line

*92 Activation, *93 Deactivation - Customer Programmable Call Forwarding Don't Answer

*98 allows a user of voicemail to access it (in most Canadian Landlines, and VoIP services)

*99 allows a user of voicemail to access it (this is used by some independent telcos).

*123 allows a user of Vonage's voicemail to access it.

*228 - Provides the ability to securely load an Authentication Key into a your wireless phone which is used to confirm and validate the identity of the wireless handset.

*272 - Wireless Priority Service - Access to Wireless Priority Service (WPS) - a nationwide cellular priority access capability in support of national security and emergency preparedness telecommunications.