Okay, so you can cast alter self on your familiar to make them into a humanoid. Familiars also understand all the languages you speak. So, can a familiar speak those languages when in humanoid form (thus having the right equipment to do so)?
No where in th. Familiar write up does it say they can un u derstand all th languages of the master. Speak with masterisnt relevant if th familiar converses with others.
But you could use the Linguistics skill to take Common (again), that would work.