In addition to communicating with the local Air Traffic Control facility, all aircraft in the Persian Gulf AOR are required to give the Iranian Air Defense Radar (military) a ten-minute 'heads up' if they will be transiting Iranian airspace.
This is a common procedure for commercial aircraft and involves giving them your call sign, transponder code, type aircraft, and points of origin and destination.
I just flew with a guy who overheard this conversation on the VHF Guard (emergency) frequency 121.5 MHz while flying from Europe to Dubai. The conversation went something like this...
Air Defense Radar: 'Unknown aircraft at (location unknown), you are in Iranian airspace. Identify yourself.'
Aircraft: 'This is a United States aircraft. I am in Iraqi airspace.'
Air Defense Radar: 'You are in Iranian airspace. If you do not depart our airspace we will launch interceptor aircraft!'
Aircraft: 'This is a United States Marine Corps FA-18 fighter. Send 'em up, I'll wait!'
Air Defense Radar: (no response ... total silence)