IMO in regards to the OPs question, it would depend on the state, city, and locale where the origin of the call resides.
Yuma AZ, 911 operator responds with "Yeah, and...?"
Denver (city & county) CO, 911 operator sends all available units - (illegal to OC)
Surrounding city of Denver CO, 911 operator may or may not ask more info, will likely get a multi officer response (been there, done that)
It all depends on the location and general public stance on handguns. If the area is gun friendly and OC is not all that uncommon, there may be a response, the 911 operator may dig for more info from the sheep. In a not so gun friendly area, where OC is uncommon, then unless there is some other major incident requiring a lot of LEO attention, then there will be a response.