Qt Code: 
  1. PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/home/arun/Documents/Subha/OCT_LIB_WORK/MCPTT_LIB_BUILD_OCT/PJSIP_LIB/lib/pkgconfig/
  2. CONFIG += link_pkgconfig
  3. PKGCONFIG += libpjproject
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Problem 1.

You are asking Qt to run pkg-config and extract the compiler and linker options for a package called "libpjproject". That should be a come from a file called "libpjproject.pc" not "pkgconfig.pc".

Does this work outside qmake?
Qt Code: 
  1. $ export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/home/arun/Documents/Subha/OCT_LIB_WORK/MCPTT_LIB_BUILD_OCT/PJSIP_LIB/lib/pkgconfig/
  2. $ pkg-config --libs libpjproject
  3. $ pkg-config --cflags libpjproject
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Problem 2.
PKG_CONFIG_PATH is not an qmake variable, it is an environment variable that pkg-config might use, This needs to set outside qmake.