How often can homing pigeons send a message to each other?

Pigeons can't send messages to each other. A homing pigeon is a kind of bird that is trained to deliver messages and letters. Through the equipment tied to the pigeon's feet, people can send instructions to the homing pigeon, take the information to the designated place and then retrieve it. This way of information transmission is faster, but it requires training and preparation in advance. So the way mentioned in the question is impossible, and it is impossible for homing pigeons to send text messages directly to each other.