This is becoming interesting. Kabuto gets a call, and he was the partner of one of Madara's actual 'men' (Kabuto and Orochimaru working with him).
If that is the case, then there are some things we can potentially glean from this if I'm not mistaken.
1.) Orochimaru may be currently working for Madara, seeing as earlier on, Kabuto wasn't 'sure that Tobi/Obito would act as planned'.
2.) It seems that the Eye of the Moon was a way to rope Obito into the plan as opposed to the end goal- why would Orochimaru agree to it otherwise?
3.) Is it possible that Hashirama was resurrected in this way to give Madara his power?
4.) Though if Obito was always intended for resurrecting Madara (Black Zetsu controlling him) then why was Nagato needed? (NVM, Obito needed to manipulate and pull the strings in preparation for Madara's return- something he didn't do- and he was a bit surprised when Kabuto pulled him out of nowhere. This constituted a setback for sure, but it all fell apart, I would guess).
Just some thoughts.