Hi
First of all, you will need to find out how many SIP channels your VoIP provider allowes (if you not sure, please let us know the name of your provider and someone can find out for you
I can't see an option within the 3CX Soft Phone its self to setup a Confrence or even a 3 way call.
X-Lite supports 3 way Calling, but again you need to also check with your VoIP Provider.