I now have a libopuscodec.a library in trunk/third_party/lib folder. Now, i include this library in my ios project but still opus is not being used. I also tried what Roberto Fichera had told me : //after pjsua_init() call. pj_str_t codec_id = pj_str( "opus/48000" ); if ( pjsua_codec_set_priority( &codec_id, PJMEDIA_CODEC_PRIO_HIGHEST ) != PJ_SUCCESS ) { fprintf(stderr, "Warning: Failed to set opus/48000 codec at highest priority\n" ); } It shows the error message. Can anyone tell what else i have to do? Thanks a lot for the help till now. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.pjsip.org/pipermail/pjsip_lists.pjsip.org/attachments/20130607/7798ab7f/attachment-0001.html>