I used the suction cup, but used a long screwdriver through the pull-ring help up with books either side piled to just lift the phone of the worksurface when I started to apple downward force on the phone. Meant that I could be more confident applying force as, if it did go suddenly, the phone would only travel the distance down to the surface. Had to add a few books as I hadn’t allowed for them compressing as I applied force.