Thanks Cardza!
I've actually seen Cellular Mitosis performed, and I think I figured out how it is done. If I'm right, then it is extremely clever, mostly because of it's boldness
However I am pretty sure that my method is different to the one used in Cellular Mitosis, as in that it is the performer who first speaks to the person on the other end of the line (at least it was that way around when I saw it

), whereas in mine the spectator can ring up and talk to the person on the other end before the performer.
Thanks again for the reply, any comments would be appreciated.