forward signal from photoelectric barrier to Amplicom PowerTel 601

Hi everybody,

I’m volunteering in a small local cinema in the north of Denmark.

As long as movies are running our personnel are carrying an Amplicom PowerTel 601 wrist band to be able to react to phone calls (the phone stays outside the auditorium).
I’m looking for a possibility to forward the signal from our light barrier on the main door to this wrist band.
Anybody got an idea how to do that?
Just some hints or ideas would be very helpful.
Thanks beforehand!

Cheers, /Thomas