Hi any body have the last firmware version of Officeserv 12? A version later than 2.75, thanks

There was nothing later then 2.75b for the os12 that I'm aware of.
Just like the 100 r2 and 500 r2.
What makes you think there is?

Hi, I think there is a version that supports ip extensions with sip protocol.

Sip extensions were never supported on these systems.
From memory (close to 10 years since I've looked at a os12) the mmc's are there, not sure if they work though.