mordor:/etc/asterisk # cat extensions.conf
[general]
static = no
writeprotect = yes
autofallthrough = no

[globals]
TRUNK=SIP/bv-trunk

[bvcontext]
exten => _X.,1,NoOp(Incoming Call from BroadVoice ${CALLERID} for ${EXTEN}@${SIPDOMAIN})
exten => _X.,2,Answer
exten => _X.,3,Background(moo1)
exten => _X.,4,Dial(SIP/100)

core set verbose 5:
    -- Executing [NXXNXXXXXX@bvcontext:1] NoOp("SIP/NXXNXXXXXX-081d9918", "Incoming Call from BroadVoice  for NXXNXXXXXX@72.1.130.34") in new stack
    -- Executing [NXXNXXXXXX@bvcontext:2] Answer("SIP/NXXNXXXXXX-081d9918", "") in new stack
    -- Executing [NXXNXXXXXX@bvcontext:3] BackGround("SIP/NXXNXXXXXX-081d9918", "moo1") in new stack
    -- Playing 'moo1' (language 'en')
[Dec 27 11:20:14] WARNING[3173]: file.c:616 ast_readaudio_callback: Failed to write frame
  == Spawn extension (bvcontext, NXXNXXXXXX, 3) exited non-zero on 'SIP/NXXNXXXXXX-081d9918'