D-Link DPH-50U Quick User Manual page 19

Within 10-20 seconds, you should see the following screen, and the telephone
connected to the DPH-50U USB Phone Adapter for SKYPE should ring. Pick
up the handset and follow the instructions. The Echo Test Service will ask you
to leave a message which will be played back immediately. This will help you
verify that the DPH-50U USB Phone Adapter for SKYPE, DPH-50U driver and
the telephone handset are all connected and installed properly.