This has been a BBRY problem for some time, i seem to remember this form BB10 onward. They use to have amazing volume for phone and music playback - to the point where one would rarely crank the volume up to 10. Somewhere along the way when there was talk of law suits for loss of hearing due to ipods and other devices, they added a screen when you would increase the volume stating something like "listening to loud volumes could potentiality damage hearing" click here to increase you volume.
There must have been an internal assessment that wanted to protect them from potential lawsuits because somewhere around the release of blackberry 10os they limited volume to a ridiculously low levels. For calls on the streets of NYC i can not use anything at less than full volume and even then it is low. Always seems ridiculous that a volume can not be made to be too loud. What's the point of the lower 70% of the levels if they are unusable???
This is not just a blackebrry thing, true of most phones these days. My Pixel suffered the same thing, you can see a big difference going back to some older devices. I would like the option to crank it up to 11