Joshua Phone is an Item in All Star Smashers. It is also quite character-specific. If Harry Bradshaw answers the phone, Joshua will curse "I kill you!" If Matthew Whitehead answers it, he will get called a crybaby, which makes him cry like one. Other characters will just have normal conversations. A full list of conversations can be found here.
While this item may seem useless, you can throw the phone to give opponents their respective effects. If it hits a wall, it will break and sound waves will fly into the air which can cause damage.