Wiccans ,for the most part ,do it with ritual.
Samhain is the most important ritual of the year,for most wiccans anyway,and that's when we call the horned god to come,to bless the new year with abundance,but it is the goddess we worship .Nothing happens without the goddess,and devotion to her is constant .
Depending upon individual beliefs,some wiccans like to call other earth dieties ,ffrom various pantheons .Artemis ,Bacchus,Athena ,Isis,are used frequently .
In religions like Santeria and voodoo,we call the deity down ,and it is alleged to possess its initiate ,so its much more face to face.
Also ,people who practice ceremonial magick,which is the basis of most OTO and Golden Dawn practices,the magician does a protective circle,and summon the demon of their choosing ,listed in the Goetia .
So I guess that's face to face ?
I am not a fan of that kind of summoning .I have used goetia in my works,but I don't "summon" them.
I use them in the same way I would use an orisha of Santeria . It's more of a request ,so ,I have no idea if anyone has ever come face to face with a goetia demon .
I am going to have to ask about this now,as I've never given it any thought before .
What sort of "currency" entices a demon or diety to act?