/usr/lib/x86_64-linux-gnu/libpjsip-simple.so is in libpjproject-dev 2.5.5~dfsg-6+deb9u1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libpjsip-simple.so.2
/usr/lib/x86_64-linux-gnu/libpjsip-simple.so.2