Nevermind... when in doubt, google everything
If anyone was wondering the same thing... "
Multicom is different from Unicom. When Multicom is used around airports, that usually means the airport has no fixed base operator. Like Unicom, pilots broadcast their position and intentions out into the area on a Multicom frequency. However, responses from other airplanes may not always be expected, and no responses will return from the ground.
Multicom's main purpose is to alert other aircraft of the pilot's intentions. Usually small planes use Multicom. Large aircraft could use it, but it would be meaningless. If the airport is too small to have a base operator, then it probably does not have enough runway space for large aircraft. Its most common frequency is 122.900, but there are many others. The problem about Multicom is if aircraft in the sky need to communicate to the ground, there is no base operator to respond. That is the primary reason most aircraft divert away from airports that use Multicom. "