Hi to all, I have followed this wiki page to intall gsmopen module http://wiki.freeswitch.org/wiki/GSMopen#Linux Installed following prerequisites packages # yum -y install alsa-lib-devel alsa-utils then, go to gsmopen directory #/usr/local/src/freeswitch/src/mod/endpoints/mod_gsmopen/gsmlib/gsmlib-1.10-patched-12ubuntu1 I wanted to compile only SMS support, no voice call. When, I compiled the source code , I am getting following error , #make ...... ...... gsm_unix_serial.cc:89: error: 'strerror' was not declared in this scope make[1]: *** [gsm_unix_serial.lo] Error 1 make[1]: Leaving directory `/usr/local/src/freeswitch/ src/mod/endpoints/mod_gsmopen/gsmlib/gsmlib-1.10-patched-12ubuntu1/gsmlib' make: *** [install-recursive] Error 1 When, I enter into following directory and trying the compile the source code, #/usr/local/src/freeswitch/src/mod/endpoints/mod_gsmopen # make I am getting following error gsmopen_protocol.cpp:5:28: error: gsmlib/gsm_sms.h: No such file or directory gsmopen_protocol.cpp:9:36: error: gsmlib/gsm_unix_serial.h: No such file or directory gsmopen_protocol.cpp:11:30: error: gsmlib/gsm_me_ta.h: No such file or directory gsmopen_protocol.cpp:16: error: ‘gsmlib’ is not a namespace-name ... ... gsmopen_protocol.cpp:3223: error: ‘DCS_DEFAULT_ALPHABET’ was not declared in this scope gsmopen_protocol.cpp:3225: error: ‘DCS_SIXTEEN_BIT_ALPHABET’ was not declared in this scope gsmopen_protocol.cpp:3226: error: ‘bufToHex’ was not declared in this scope make[1]: *** [gsmopen_protocol.o] Error 1 make: *** [all] Error 1 I do not know, what I am doing wrong. Anyone please help me regarding this. -- Regards Venkatesan OV.