I was going to file a JIRA, but I'm not running on most recent commit of FreeSWITCH. I have not been able to reproduce this issue on-demand, but it has happened sporadically in both 1.4 and as of yesterday 1.7. A FreeSWITCH box will be running any number of calls (I've seen this happen with a handful and with hundreds) and will crash on WAV playback. The second-to-last message in the log file has been: [ERR] switch_core_codec.c:784 Decode Codec is not initialized! in every instance of this failure. Our use case is we originate calls via mod_event_socket and with an inline dialplan that starts spandsp_start_tone_detect (for beep detection) and then plays a playback string of silence followed by one or more WAVs (8-bit u-law). I have not been able to narrow the culprit down to one specific call. In the most recent crash all calls had negotiated to PCMU or PCMA. Any thoughts on how I could reproduce this so I can file a proper bug report? Some more info is below, and I'd be happy to provide any more information I can. info: * Amazon EC2 c4.xlarge instance * Debian 8.2 (jessie) * commit 2cb7188c1733a6524e5852f95bb71f12e0ffcc18 * FreeSWITCH version: 1.7.0+git~20151209T003048Z~2cb7188c17~64bit (git 2cb7188 2015-12-09 00:30:48Z 64bit) stack trace: #0 0x00007fe06a4a3750 in switch_core_session_read_frame (session=0x7fe0259a9078, frame=0x7fdfe0dd6090, flags=1641139939, stream_id=1762346489) at src/switch_core_io.c:501 #1 0x00007fe06a52934a in switch_ivr_play_file (session=0x7fe0259a9078, fh=0x7fdfe0dd6850, file=0x7fdfe0dd6810 "", args=0x7fe0690b45f9 <__lll_unlock_wake_private+25>, args@entry=0x7fdfe0dd6810) at src/switch_ivr_play_say.c:1721 #2 0x00007fe061362343 in playback_function (session=0x7fe0259a9078, data=<optimized out>) at mod_dptools.c:2810 #3 0x00007fe06a49e81a in switch_core_session_exec (session=0x7fe0259a9078, application_interface=0xba4340, arg=0x7fe0259a5170 "silence_stream://1000!718946f17f2b6e4638d510540952d58e.wav!silence_stream://5000") at src/switch_core_session.c:2783 #4 0x00007fe06a49edb8 in switch_core_session_execute_application_get_flags (session=0x0, app=0x7fe0259a5160 "playback", arg=0x7fe0259a5170 "silence_stream://1000!718946f17f2b6e4638d510540952d58e.wav!silence_stream://5000", flags=0x0) at src/switch_core_session.c:2653 #5 0x00007fe06a4a1d42 in switch_core_standard_on_execute (session=<optimized out>) at src/switch_core_state_machine.c:283 #6 switch_core_session_run (session=0x7fe0259a9078) at src/switch_core_state_machine.c:539 #7 0x00007fe06a49c0be in switch_core_session_thread (thread=<optimized out>, obj=0x7fe0259a9078) at src/switch_core_session.c:1629 #8 0x00007fe06a497e5d in switch_core_session_thread_pool_worker (thread=0x7fe0259cdd80, obj=0x0) at src/switch_core_session.c:1692 #9 0x00007fe06a579590 in dummy_worker (opaque=0x7fe0259cdd80) at threadproc/unix/thread.c:151 #10 0x00007fe0699ce0a4 in start_thread (arg=0x7fdfe0dd7700) at pthread_create.c:309 #11 0x00007fe0690a804d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111 Thank you, Adam Johnston