probado como me indicas
sgc-01*CLI>
-- Executing [50@sofphone:1] MusicOnHold("SIP/10-083b72a8", "default") in new stack
[Jul 1 11:20:42] WARNING[27227]: res_musiconhold.c:660 get_mohbyname: Music on Hold class 'default' not found
[Jul 1 11:20:42] WARNING[27227]: res_musiconhold.c:660 get_mohbyname: Music on Hold class 'default' not found
[Jul 1 11:20:42] WARNING[27227]: res_musiconhold.c:597 moh0_exec: Unable to start music on hold (class 'default') on channel SIP/10-083b72a8
-- Executing [50@sofphone:2] Hangup("SIP/10-083b72a8", "") in new stack
== Spawn extension (sofphone, 50, 2) exited non-zero on 'SIP/10-083b72a8'
exten=> 50,1,MusicOnHold(default)
exten=> 50,n,Hangup