I'm not able to add a device, and the doorbell beeps twice when I try. What's wrong?
That means you've exceeded the number of devices that your doorbell can store. The number of device connections vary depending on the model. Here's a quick reference guide:
Series 3 RDWL311 = 2
Series 3 RDWL313 = 4
Series 5 RDWL515= 4
Series 9 RDWL917= 6