Code numbers

General Indicators
| General | |
| Outside line | 0 + call number |
| Outside line private | 1 9 + call number |
| Voice mail | 71 |
| Paging system for pagers without display | 1 4 1 + 4-digit pager number |
| Paging system for pagers with display | 1 4 2 + 4-digit pager number + callback number |
| Paging system for pagers with display | 1 4 3 + 4-digit pager number + automatic post-dialing of your own number |
| Call transfer university hospital internal | 1 0 |
| Call transfer university hospital external | 8 0 - 0 |
| Call transfer RWTH internal | 1 3 |
| Call transfer RWTH external | 8 0 - 1 |
| Police (via department) | 1 1 0 |
| Fire department - university hospital | 1 1 2 (separated from RWTH) |
| Fire department - RWTH | 1 1 2 (separated from university hospital) |
| Emergency call | 1 1 3 |
| General disturbances - university hospital | 1 1 5 |
| General disturbances - RWTH | 1 1 6 |
| Disturbances phone - university hospital | 1 1 7 (separated from RWTH) |
| Disturbances phone - RWTH | 1 1 7 (separated from university hospital) |
| Time check | 1 1 9 |
Function Indicators
| Call forwarding | |
| Immediate call forwarding | * 1 1 followed by number of target extension |
| Call forwarding when busy | * 1 2 followed by number of target extension |
| Call forwarding after delay (20 sec) | * 1 3 followed by number of target extension |
| Call forwarding after delay/when busy | * 1 4 followed by number of target extension |
| Delete call forwarding | * 1 0 |
| Group switching | |
| Log into group | * 2 6 |
| Log off group | * 2 5 |
| Retrieve calls | |
| Retrieve a call (selective) | # * + number of the ringing extension |
| Retrieve a call in a group (non-selective) | # # |
| Convenience function | |
| Query callback list | * 6 1 |
| Callback of last caller | * 6 2 |
| Programming functions | |
| Display charge information: Used charge information will be displayed on the device screen | * 3 0 |
| Program personal password (default 0000) | * 2 9 |
| Lock phone. After locking device no outgoing external calls can be conducted | * 3 3 |
| Unlock phone | * 3 3 + password |
| Adjust display contrast | * 3 8 |
| Enter appointment reminder | * 6 5 + time (4-digit - SSMM) |
| Delete appointment reminder | * 7 5 |
| Post-dialing | |
| DTMF dialing end-to-end | * * 8 |
| Initiate callback when free or when busy | 1 |
| Toggling between 2 calls. One interlocutor is in the queue while you are talking to the other interlocutor. | 2 |
| Conference switching 2 persons (3 internal, 2 internal + 1 external or 1 internal + 2 external interlocutors) can talk simultaneously. | 3 |
| Call waiting protection. There is no alter tone when a second caller is in the queue during an existing connection. | * 4 |
| Call waiting control. When calling a busy extension, an alter tone can be signaled in the existing call. | 4 |
| Consultation call | 8 |

