Phone is a natural sign. Take your dominant 'Y' hand (the letter 'Y' in ASL), with the rest of the fingers drawn into a fist while the thumb and pinkie finger are sticking out, and hold this hand up to the side of your face, nearly touching your mouth and ear.
Teach your baby the phone sign to indicate that you are about to place a call to family or friends. You can also teach the sign if your baby has a toy telephone.
Phone is a fun sign to teach your baby or toddler, especially if your child has the props to practice making a phone call to some imaginary friend.