In Shmeul Aleph Perek Gimel Shmuel becomes a Navi. Pasuk Gimel Pasuk Daled it says that Hashem called to Shmuel and he(Shmuel) said Hineni. But them Pasuk Hey continues by saying the Shmuel ran to Eli because Shmuel thinks Eli is calling him. Then for two more times Hashem calls Shmuel by his name and then runs to Eli who sends him back before Eli finally realizes it is Hashem who is calling Shmuel. Each time Shmuel speaks to Eli he says Hineni.
How do we understand that Shmuel seems to respond to Hashem in Pasuk Daled and then runs to Eli because he thinks Eli called him? Who does Shmuel think he is speaking to?