I would have liked to train my dog to ring the doorbell when it wanted back into the house, but there is a better way. The Wireless Doormat Chime was created by Swann, a company known for its at-home security products, however it would also come in handy for pet owners who frequently let their dogs and cats slip outside. If they hop back on the mat, a chime will sound from the wireless indoor unit, which can be placed anywhere within 30 meters of the mat, so no matter where you are in the house, you will know that your pet wants back in.
Available for $34.99 at Swann.