Kirk was already on his way down towards security when the comm came through. His mind was completely wrapped up in other things, namely (unknowingly!) the two people in the very conference room he was thinking of. He needed to tell security about Nero...

All he heard was a female's voice, and 'captain'.

"Kirk here. Busy, unless this is an emergency." He said without much thought behind it. It could have been anyone, but it wasn't Jim, Spock, or one of the security people he knew was in charge down in the brig right now so his mind dismissed it without a second thought.