Setting up a conference call is largely similar to conducting a call transfer.
When you answer a call, you can select the ‘conference’ button from the row of options at the top of your phone keypad.
This places the caller on hold, signaled by a dial tone. You will then be prompted to dial the number of the extension that you wish to add into the call.
When they answer, press ‘Conference’ again. You will now find yourself in the conference call. To leave, simply hang up.