Hi, I use back PJSIP 1.0.3 and remove the --disable-sound from compile.sh, but after I remove it although it did compile the iphonesound.c, but in the compile log it states "iphonesound.o has no symbols". So from few days of failure with PJSIP 1.4 and 1.5 i discover something. - On PJSIP 1.4 and 1.5, we should use the iphonesound-20091226.c (but I still face the make error during compile) - On PJSIP 1.0.3 we should use ipodsound.20080519.c with patches from http://stackoverflow.com/questions/1460674/pjsip-on-iphone-os-3-0-how-to-port-sound to make the sound file works. So I switched back to my last successful cross compile PJSIP 1.03 file set, and did the correction above using ipodsound.c, apply the patch and change all "ipod" term within the file to "iphone", and finally in the my application console log it recognize iPhone Sound Device and the sound works. Thanks to Shayne, Samuel and Torsten for being patience with me and help me through the trouble. Although I still cant quite the PJSIP 1.4 to compile right, but at least having a workable 1.03 to use for my project. Currently my application log keep showing the Master/sound underflow? 02:32:41.862 Master/sound Underflow, buf_cnt=85, will generate 1 frame 02:32:42.140 Master/sound Underflow, buf_cnt=80, will generate 1 frame 02:32:42.427 Master/sound Underflow, buf_cnt=267, will generate 1 frame 02:32:42.704 Master/sound Underflow, buf_cnt=25, will generate 1 frame Should I change the frm_per_pkt value? If so what value should I change to? Thanks again to Shayne, Samuel and Torsten. Regards Jin Li