Once you are connected to a call, you will notice this icon below the recipient's name.

Click on the icon to add another call.

After clicking, the dial pad will expand with another window and your first call will automatically be placed on hold. 

Dial your next call or select an agent through the agent list directory. 

Once you connect to your second call, two options will become available. 

Image above demonstrates a conference call in progress.

Call Transfer: Upon clicking the icon, you will transfer your first call (on hold) with your second call.Conference Call: You have allowed all parties to participate in the conversation.

With multiple calls made, you have the ability to toggle between calls by pressing the  to place your current call on hold, and pressing the  on the previous call to resume.