Yes, the system records and stores everything, 911 call and radio communications.
And most dispatch consoles (and call taker positions) have instant recall, which allows a dispatcher or call taker to replay a few minutes of audio (or the last several calls, however it's set up).
Problem is, if audio didn't make it from Point A to Point B, it may not have made it to the console reliably, and with phones ringing and the usual goings-on of a dispatch center around you, it's pretty tough to track it down on the fly. With the chaotic conditions (and probable technical issues) that must be in Cincinnati's 911 center due to the dramatic understaffing, I can totally understand how some information could get missed.
Unfortunately, the feeling out in the public (and by elected officials, who generally only give a damn when something goes wrong, like now) has often been along the lines of "answering phones and radios, how tough can that be?" I was a police/fire/EMS dispatcher for 22 years, and I can tell you it's a very tough, stressful job, which is one of the reasons there's very high turnover and lots of overtime due to a shortage of personnel. And when something like this happens, it's often just as tough on the dispatcher as for the loved ones, because they couldn't do more.
In my mind, dispatchers still don't get paid nearly enough, or get enough respect for the incredibly tough job they do.
