Recently I have bought a Byron BY32 doorbell converter. As I wanted to keep my original bell push and chime, I finally found this product. You connect it parallel to your existing chime and it sends a RF code when the button is pushed. I have debugged the code with the homeduino plug-in and found out it was a Pir3 protocol. The weird thing is that the device sends two different codes alternately. The solution for this is to define 2 protocol blocks.
Byron Website with product info: Byron BY32 Doorbell Converter
Topic with solution for alternating sent RF codes: Byron Doorbell