I'm pretty sure this was a feature of an old dumbphone, you could set it up so that holding down the number 5 (say) on the key pad would trigger a 'call'. Might have been a Samsung?
I hand an old Nokia (That had a sliding keyboard !!) with this feature (press down volume 4 times), it also had a scheduling feature with personalized ring-tone, number and display name!
I have a Samsung GT E1200 and the fake call is triggered after a configurable timeout by pressing the down button four times while the screen is locked.