Previously, we explained that we Jews believe that Moshe attained the highest level of prophecy (see here).
One of the differences between Moshe and all other prophets was that Moshe could receive Prophecy whenever he wished. He did not need to bring himself to a state of prophetic concentration since he was in a permanent state of prophetic concentration (See, Rambam, Yesode haTora 7:6).
I will explain this concept with an example.
Prophecy is a phone-call from God. Now, you can only get a phone call, any phone call, if you have a functioning phone. To be a prophet, one had to reach the highest level of huan perfection (remember: "wealth, wisdom and strength"? See here). In this sense, "to have a phone" means to have reached this high level of human perfection. Many people mightimagine that they receive (or deserve to receive) a message from God. Which in light of what I just explained, it might be considered a bit arrogant, unless one feels that he or she have actually achieved that level of human perfection. Without that "phone" you can not receive God's message!
Now, once an individual possesses 'an active phone', he will not necessarily get a call from HaShem! Being a prophet means "achieving a level which deserves prophecy", not necessarily the actual reception of a prophetic message. Calling or not calling the prophet is God's prerogative: "All prophets (except Moshe) could not receive prophecy whenever they desired. It all depended on God's will. A prophet might wait days and years, and still not receive prophecy" (Rambam, commentary to the Mishna).
Moshe Rabbenu, however, could receive a call from God at will. "Whenever he wished, he could be enveloped by divine inspiration, and prophecy will descend upon him" (Yesode haTora 7:6) enabling him to be in constant contact with God.
Preparing ourselves for Yom Yerushalaim (Sunday May 20, 28 of Iyar)