The flight crew reported during flight in a older model 737 they lost all communication with ATC usi...

Narrative:

While in route to ZZZ in a straight-wing older model 737 with no ability to have a 'hot' intercom microphone; I first began to hear some audio clicking which is not totally unusual; but then the radio chatter went quiet.we tried contacting center by switching comms and frequencies; transmitting in the blind; using 'guard;' all pretty much with negative results.I instructed my first officer to use ACARS to communicate with dispatch; but this was complicated by the fact that there is only one ACARS mdcu on the first officers side; so I had to verbally yell transmission content. We notified dispatch of our problem.every five to ten minutes we would start hearing other aircraft transmissions; but could only establish ATC communications intermittently and for brief periods. This continued for most of the flight. It was very frustrating.we were able to make ATC aware of our problem during the brief moments that there was contact. We agreed and confirmed our lost comm procedure so airspace would be cleared. During the protracted outages we did squawk 7600; but when ATC contact was established they would request we go back to our assigned squawk. Then comm was lost again and back to 7600!for the last approximate 15 minutes with center; we got more steady use of the radio; continued on to [destination] and landed.

Original NASA ASRS Text

Title: The Flight Crew reported during flight in a older model 737 they lost all communication with ATC using the normal radios. Communication became intermittent for brief moments.

Narrative: While in route to ZZZ in a straight-wing older model 737 with no ability to have a 'hot' intercom MIC; I first began to hear some audio clicking which is not totally unusual; but then the radio chatter went quiet.We tried contacting Center by switching COMMS and frequencies; transmitting in the blind; using 'guard;' all pretty much with negative results.I instructed my F/O to use ACARS to communicate with Dispatch; but this was complicated by the fact that there is only one ACARS MDCU on the F/Os side; so I had to verbally yell transmission content. We notified Dispatch of our problem.Every five to ten minutes we would start hearing other aircraft transmissions; but could only establish ATC communications intermittently and for brief periods. This continued for most of the flight. It was very frustrating.We were able to make ATC aware of our problem during the brief moments that there was contact. We agreed and confirmed our lost COMM procedure so airspace would be cleared. During the protracted outages we did squawk 7600; but when ATC contact was established they would request we go back to our assigned squawk. Then COMM was lost again and back to 7600!For the last approximate 15 minutes with Center; we got more steady use of the radio; continued on to [destination] and landed.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1374567
Time
Date	201607
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Air/Ground Communication
Person 1
Function	Captain
Experience	Flight Crew Last 90 Days 234
Person 2
Function	First Officer
Experience	Flight Crew Last 90 Days 218
Events
Anomaly	Aircraft Equipment Problem Less Severe

The flight crew reported during flight in a older model 737 they lost all communication with ATC using the normal radios. Communication became intermittent for brief moments.