Dear all: I can successfully build pjsip 1.1 under mingw+msys,but when i use pjsip in my own app, a very short code as following: #include <stdio.h> #include <stdlib.h> #include <pjlib.h> #include <pjlib-util.h> #include <pjnath.h> #include <pjsip.h> #include <pjsip_ua.h> #include <pjsip_simple.h> #include <pjsua-lib/pjsua.h> #include <pjmedia.h> #include <pjmedia-codec.h> int main() { pjsua_create(); printf("Hello world!\n"); return 0; } when I build it ,it occurs many erros such as: Linking console executable: bin\Debug\TestCPJ.exe ..\..\..\..\SDK\sip\PJSIP1.1\Or\pjprojectmsys\pjsip\lib\libpjsua-i686-pc-mingw32.a(pjsua_core.o):pjsua_core.c:(.text+0x33): undefined reference to `_pj_strerror' ..\..\..\..\SDK\sip\PJSIP1.1\Or\pjprojectmsys\pjsip\lib\libpjsua-i686-pc-mingw32.a(pjsua_core.o):pjsua_core.c:(.text+0x38): undefined reference to `_pj_log_get_level' ..\..\..\..\SDK\sip\PJSIP1.1\Or\pjprojectmsys\pjsip\lib\libpjsua-i686-pc-mingw32.a(pjsua_core.o):pjsua_core.c:(.text+0x5f): undefined reference to `_pj_log_1' i now using CodeBlocks and added link libraries and search paths. thank you very much!