Additional transmitter as an emergency bell

Have the Mistral radio chime 300M as doorbell and I am totally thrilled. Good quality and makes a durable impression. Each transmitter can easily be assigned its own ring signal. It has offered to buy an additional transmitter for living in the house pensioner. The radio Gong rapidly adapted to this transmitter to alarm, stations in the Senior beside the bed and again a little more security for emergencies. It works great!
This transmitter also (for 250 meters) has been going through some walls, opt for stronger transmitter if necessary (for 500 meters). I have it tested first with the original sender of the gong, which was sufficient in my case, and then ordered the corresponding additional transmitter. MfG