Hello Tedelen,
Be sure to meet all the requirements of the phone to make calls and to be fully operational. These requirements can be found
here (Requires Adobe Acrobat Reader).
To make a phone call follow these instructions:
Making calls with the Handset1. Pick up the handset and the phone automatically selects the priority line. If the priority line is occupied, it selects an open line.
OR
Pick up the handset and press a LINE button to select a line.
2. Wait for a dial tone, then dial a phone number.
3. Hang up the handset when finished.
Making Calls with the Speakerphone1. Press the SPEAKER button and the phone automatically selects the priority line. If the priority line is occupied, it selects an open line.
OR
Press a LINE button to select a line.
2. Wait for a dial tone then dial a phone number.
3. Press SPEAKER button when finished.
If you are having problems refer to the given link to the User Guide.
-bsalamakha