Good afternoon,
First, have you checked the RC Service Status? If you have, and there is no reported issue there can be outside reasons impacting the call quality. For example, making a call with your cell phone the cellular service will ping different towers to get a connection. The same is true with VOIP.
There can be congested network routers, etc. causing the data (spoken word) to sound disjointed or even delayed. If you have administrator rights, you can look up the call in Analytics and it will display on a map with the value of the quality. This will give you some reason for the crackling.
I have experienced similar in my office and the first response to me will be "there is a problem with RC." This information is helpful when communicating with associates it is not RC call quality.
I hope this helps.
Have a great afternoon
