While normally appearing to be a simple figurine in the shape of a carved songbird, when the owner speaks its command word (in Thieves Cant, of course), the songbird will spring to life. 
Once active, the owner can speak a message (No longer than 30 seconds in length) and telepathically command the songbird where to go and who to give the message to. 
If the recipient wants to, they can respond to the Songbird and the owner will be able to hear the response as if it were being spoken to them. 

Once used, the songbird cannot be used until it returns. They may take up to a day depending on how long it has had to travel.