Note: You do not need to dial 9 to make an external call.
Open Web Client
Search or browse for the person you want to call
Select the handset icon button next to the person's name.
OR
Use the dialer, and manually key in the number.
The Web Client triggers the call on your deskphone if selected via the phone selector toggle.
See also the video tutorial below and additional video tutorials here:
Dial the number on the keypad and press the send or enter button. (depending on the model of phone the 'send' button nay be an 'OK' or a circle in the middle of the arrow pad)
Open the 3CX App on your phone.
Press 'Contacts'
Select person and press the handset next to person's name.
OR
Use the keypad dialer and manually type in the number