Volume Button Broken, manual reset of in-call volume

[acs1989]

Hey Forum-

Ok so I dropped my phone and broke the up key on my thunderbolt. I can now only quiet someone on the in-call volume but can't seem to raise the volume. I have messed around in the settings, sound area but no clue as how to reset the in-call volume with out the volume key. Any one know how to manually raise the in call volume?

Thanks!