Internal calls: Enter the station number.
External calls: Enter the external code and the station number. 

The other party answers with speaker:

Lift the handset. 

On-hook: Use speakerphone mode (not available with optiPoint 500 economy and optiPoint 500 basic). 

The called party does not answer or is busy:

Press the key. The LED goes out. 

Your system may also be programmed so that you have to press the Internal key before you dial an internal number. To call an external party, you have to enter an external code before dialing the party's telephone number (Prime Line is not active; contact System Support).

If this feature is configured (contact System Support), a connection is not attempted immediately when a station number is entered. This means that you can correct the number if necessary.
The station number is only dialed at your specific request. 

Internal: enter station number.
External: enter external code and station number. 

Dialing entered/displayed numbers:

Lift the handset. 

Confirm. 

Correcting numbers entered:

Select and confirm.
The last digit entered in each case is deleted. 

Enter the required digit(s). 

Canceling en-bloc sending:

Select and confirm. 

Press the key. The LED goes out. 

Press the key.