Asterisk не воспроизводит записаное с помощью Record()

Записываю с помощью Record() сообщение, потом хочу прослушать но...

    -- Executing [10@recorder:4] Record("SIP/101-0000000b", "/var/lib/asterisk/sounds/prerecorded/prerecorded_10.gsm") in new stack
    -- <SIP/101-0000000b> Playing 'beep.gsm' (language 'en')
    -- Executing [10@recorder:5] Wait("SIP/101-0000000b", "1") in new stack
    -- Executing [10@recorder:6] Playback("SIP/101-0000000b", "/var/lib/asterisk/sounds/prerecorded/prerecorded_10.gsm") in new stack
[Jul  8 18:54:47] WARNING[3490][C-0000000b]: file.c:701 ast_openstream_full: File /var/lib/asterisk/sounds/prerecorded/prerecorded_10.gsm does not exist in any format
[Jul  8 18:54:47] WARNING[3490][C-0000000b]: file.c:1017 ast_streamfile: Unable to open /var/lib/asterisk/sounds/prerecorded/prerecorded_10.gsm (format (ulaw)): No such file or directory
[Jul  8 18:54:47] WARNING[3490][C-0000000b]: app_playback.c:480 playback_exec: ast_streamfile failed on SIP/101-0000000b for /var/lib/asterisk/sounds/prerecorded/prerecorded_10.gsm

почему так случается?