B737-700
Flight Crew Last 90 Days 120; Flight Crew Type 4200
Aircraft Equipment Problem Less Severe
Air Traffic Control Issued Advisory / Alert; Aircraft Equipment Problem Dissipated; Flight Crew Became Reoriented
Aircraft
While transiting through Cleveland Center's airspace; we received an ACARS message from Dispatch stating that ATC thought we had a stuck MIC. The Captain deselected his Push-To-Talk yoke switch from the hot MIC ICS position to get a radio check with ATC. As soon as he did that; ATC reported back loud and clear and that we were the only aircraft they had been unable to check with yet. So; that means we were probably the ones with the hot MIC. There were no other indications of a hot MIC the rest of the flight and we could not duplicate it again no matter how many times the Captain cycled the PTT switch. It is unknown as to how long we had the hot MIC and how much our situation and conversation impacted other ATC communications. This is the third time that I have been a crew member on an aircraft with a stuck MIC. In all of these situations; we were trying to use the PTT yoke switch to improve crew coordination via ICS hot MIC. However; in all of these situations; we; as the flying crew members have had no indication that our switches were stuck somehow activating both ICS and VHF simultaneously. The PTT yoke switch seems to be well intentioned; but poorly engineered. Accelerating the program to replace the communication panels with the hot MIC selector on the center pedestal would be worthwhile in preventing future incidents such as this one. Also; it would be helpful to have either a light on the VHF radio panel or a visual annunciation on the PFD to show that a transmission is taking place.  All of these require money; so in the interim; disabling the PTT hot MIC function might be necessary as well.
B737 First Officer reports receiving an ACARS message that an aircraft on the current ATC frequency has a stuck mic. A radio check by the Captain using his PTT switch clears the problem.