Here is how to archive both:
Call center portal (pbxapps.primus.ca/callcentre)
1- make your outbound call
2- put call on hold
3- make a second outbound call
3- now a conf option will appear on the 1st call that was put on hold
4- click the conf button
All parties will now be on conference
From hardware (HPBX Polycom Phone)
1- make outbound call
2- put call on hold
3- click on transfer
4- dial the 2nd number
5- once 2nd number picks up, click the more button on the screen
6- click conf button
All parties will now be on conference