Banded makes an awesome lightweight technical turkey button up shirt with great pockets - one of which on the right side of the shirt is magnetic and after putting the lanyard around one's neck, you can tuck the wingbone/trumpet call into that magnetic pocket. Any pocket would suffice to do the same, but that magnetic pocket makes for being able to get to it quick and not having to full around with a button or velcro in the heat of battle.
Regardless - The absolutely best (safest) place you can carry a wingbone/trumpet is around your neck on a lanyard. And you always have fast and easy access to it as well.