You could have streched that our by denying it was a 185. It could have been a 360 or probably any of the other members of the Desiro family. I've seen that device on a 360 and assume that all other Desiros have them!
But that would be lying :P
Its one of the lift up flap things to speak to driver - I wouldn't actually be sure of whether all the other Desiros have them or not and I deliberately cropped out the surroundings so no-one could get it from the seat pattern!