Can others hear?

[Frogger]

When I am on a call for a long while (especially long hold times at government agencies such as CRA) the hold music often cuts in and out but even more concerning is that voices of other people talking cut in and out; it seems like I am listening in on others' conversations even though it's relatively garbled and usually only a few seconds at a time so hard to make out what they are saying. (It's definitely NOT someone answering and introducing themselves.) Does this mean others can hear my conversations too?