I am running with Asterisk 13.9.1 on FreePBX. Whenever an incoming call is received, then that call is transferred to another internal extension (B), the caller hears silence, and if extension B does not pick up, the caller is not transferred to voicemail. The extension just rings for about 1 minute or more, and then disconnects the caller without ever going to voicemail. This only seems to happen on calls that are transferred. I captured what happens on the console when a call transfer is initiated.
Connected to Asterisk 13.9.1 currently running on Server1 (pid = 1622)
== Extension Changed 416[ext-local] new state Hold for Notify User 415
-- Started music on hold, class 'none', on channel 'Local/415@from-queue-0000010e;2'
[2016-07-22 15:58:35] WARNING[9765][C-00000fae]: format_wav.c:149 check_header: Read failed (type)
[2016-07-22 15:58:35] WARNING[9765][C-00000fae]: file.c:472 fn_wrapper: Unable to open format wav
[2016-07-22 15:58:35] WARNING[9765][C-00000fae]: res_musiconhold.c:361 ast_moh_files_next: Unable to open file '/var/lib/asterisk/moh/.nomusic_reserved/silence': No such file or directory
-- Stopped music on hold on Local/415@from-queue-0000010e;2