I'm trying to figure out which functions from one C library are being used by C project. Does anyone have a simple solution?

I'm trying to figure out which functions from one C library are being used by C project. Does anyone have a simple solution?

To be specific, I want to know which function/types in libpri and being used in the Asterisk project. I'm not traditionally a C programmer, but I know some basic stuff because I took a class in college.