Heres some food for thought for you, and good news I hope

First the HE306, manual here http://media.homeeasy.eu/file/pdf/HE-306%20Door%20Chime%20V1.pdf. When you pop the back off the door bell switch there is a rotary switch A-P which allows you to set the Housecode. You can use any housecode to pair it with the plug in sounder. The sounder makes a double ding dong when the button is pushed, and also a lamp plugged into the socket goes on and off twice

I was doing some testing on Dereks RF Receiver module last year, similar to this in the shop

http://www.homeautomationhub.com/content/homeeasy-rf-receiver,

but with two interchangeble chips for decoding both Home Easy and BBSB as descibed in this section of the wiki

http://www.dbzoo.com/livebox/xap_serial#rf_receiver_notes,

and I recall there was something odd about the doorbell, but could not find the relevant testing notes.

At some point I managed to blow up the RF module on the receiver but have just had replacements delivered so I have hooked it up it up again tonight.

The odd thing I almost rememberd is that the BBSB chip decoded the RF where the HomeEasy one did not. It always decoded the bell push as

BBSB,P,8,S1   

ie ByeByeStandby HouseCode 8 on,  where housecode is set by the rotary switch.

So you could use the HE306 as it stands and detect the RF using the Serial RF Receiver or you could use the sounder and pair it with a command from the HAH created using the RF Helper - http://www.dbzoo.com/public/rf-helper.html and the bell button at the same time or any combination of bell button(s)  sounder(s) and HAH

As an alternative if you just wanted an RF Switch then the HE305 magnetic door contact switch could be easily hacked to replace the on board reed relay with contacts from a conventional bell button. You would receive the signal with the same RF Receiver mentioned above

HTH

kevint

PS only one RF Receiver in stock right now ... <grin>

PPS Pics of my test RF Receiver are here

http://www.flickr.com/photos/netcompsys/sets/72157625025878672/