Updated June 2019
Note: This feature is currently only available using Firefox as your browser.
Once logged into app.onsip.com (in Firefox), start a voice call.
Once the call is active, click on the “+” sign button (the 'Conference' button) on the right side of the call handling options.
Enter the phone number, extension, or SIP address of the third user you wish to add to the conference in the text field that appears below. You can access a phone keypad by clicking on the keypad icon. Also, if you want to conference in a person who is in your Contacts list, simply start typing in her name and select the contact from the dropdown that appears.
Click “Add to call” or hit enter.
When you are ready to begin the 3-way call, click on the "Resume" button for the call that is On Hold (it's the call card on the left sidebar that is colored in gray). You are now on a 3-way call in Firefox (you'll know because both of the call cards on the left sidebar will be in red):
If you wish to end a call with any of the two participants, you can click the “End” button on the particular call's card on the left sidebar. If you wish to end the call for all parties, click on the red “End Call” button on the active call screen.