asterisk users - Aug 2010 - Asterisk 1.6 Displaying BackGround() in call trace but no audio is heard from caller

Thought a different succinct subject line must drum up an answer or two...

Also, this has been tested from two different carriers: We're getting
an average of 2/10 call success rate.

---------- Forwarded message ----------
From: Joe Wood <schmoe at gmail.com>
Date: Thu, Aug 26, 2010 at 6:58 PM
Subject: Asterisk 1.6 Displaying in Debug that it is playing a ulaw
file using BackGround() but no audio is heard from the phone
To: Asterisk Users Mailing List - Non-Commercial Discussion
<asterisk-users at lists.digium.com>


First off, let me first say that this is not a one-way audio problem.
Sometimes I can get 'her' to speak to me, other times I can't for a
long time.

I'm just using a very simple system to dump people into MeetMe().
Nothing fancy.

I do have the following in my modules.conf:

preload => format_mp3.so
preload => codec_ulaw.so
preload => format_pcm.so

My extensions.conf looks like:

[general]
autofallthrough=yes
static=no
writeprotect=no
extenpatternmatchnew=yes
clearglobalvars=no


[conference-calls]
exten => s,1,Answer()
exten => s,n,Background(welcome)
exten => s,n,Background(and)
exten => s,n,Background(thank-you-for-calling)
exten => s,n,Background(conference-reservations)
exten => s,n,Wait(2)
exten => s,n,Background(enter-conf-pin-number)
exten => s,n,WaitExten(10)
exten => i,1,Playback(pbx-invalid)
exten => i,n,Goto(conference-calls,9000,1)
exten => t,1,Playback(vm-goodbye)
exten => t,n,Hangup()

exten => ${EXTEN},1,Meetme(${EXTEN})


?== Using SIP RTP CoS mark 5
? ?-- Executing [s at conference-calls:1]
Answer("SIP/2063161626-00000001", "") in new stack
?== Using SIP RTP CoS mark 5
? ?-- Executing [s at conference-calls:1]
Answer("SIP/2063161626-00000002", "") in new stack
? ?-- Executing [s at conference-calls:2]
BackGround("SIP/2063161626-00000001", "welcome") in new
stack
? ?-- <SIP/2063161626-00000001> Playing 'welcome.ulaw' (language
'en')
? ?-- Executing [s at conference-calls:2]
BackGround("SIP/2063161626-00000002", "welcome") in new
stack
? ?-- <SIP/2063161626-00000002> Playing 'welcome.ulaw' (language
'en')
? ?-- Executing [s at conference-calls:3]
BackGround("SIP/2063161626-00000001", "and") in new stack
? ?-- <SIP/2063161626-00000001> Playing 'and.ulaw' (language
'en')
? ?-- Executing [s at conference-calls:3]
BackGround("SIP/2063161626-00000002", "and") in new stack
? ?-- <SIP/2063161626-00000002> Playing 'and.ulaw' (language
'en')
? ?-- Executing [s at conference-calls:4]
BackGround("SIP/2063161626-00000001",
"thank-you-for-calling") in new
stack
? ?-- <SIP/2063161626-00000001> Playing
'thank-you-for-calling.ulaw'
(language 'en')
? ?-- Executing [s at conference-calls:4]
BackGround("SIP/2063161626-00000002",
"thank-you-for-calling") in new
stack
? ?-- <SIP/2063161626-00000002> Playing
'thank-you-for-calling.ulaw'
(language 'en')
? ?-- Executing [s at conference-calls:5]
BackGround("SIP/2063161626-00000001",
"conference-reservations") in
new stack
? ?-- <SIP/2063161626-00000001> Playing
'conference-reservations.ulaw' (language 'en')
? ?-- Executing [s at conference-calls:5]
BackGround("SIP/2063161626-00000002",
"conference-reservations") in
new stack
? ?-- <SIP/2063161626-00000002> Playing
'conference-reservations.ulaw' (language 'en')
? ?-- Executing [s at conference-calls:6]
Wait("SIP/2063161626-00000001", "2") in new stack
? ?-- Executing [s at conference-calls:6]
Wait("SIP/2063161626-00000002", "2") in new stack
? ?-- Executing [s at conference-calls:7]
BackGround("SIP/2063161626-00000001",
"enter-conf-pin-number") in new
stack
? ?-- <SIP/2063161626-00000001> Playing
'enter-conf-pin-number.ulaw'
(language 'en')
? ?-- Executing [s at conference-calls:7]
BackGround("SIP/2063161626-00000002",
"enter-conf-pin-number") in new
stack
? ?-- <SIP/2063161626-00000002> Playing
'enter-conf-pin-number.ulaw'
(language 'en')
? ?-- Executing [s at conference-calls:8]
WaitExten("SIP/2063161626-00000001", "10") in new stack
? ?-- Executing [s at conference-calls:8]
WaitExten("SIP/2063161626-00000002", "10") in new stack
? ?-- Timeout on SIP/2063161626-00000001, going to 't'
? ?-- Executing [t at conference-calls:1]
Playback("SIP/2063161626-00000001", "vm-goodbye") in new
stack
? ?-- <SIP/2063161626-00000001> Playing 'vm-goodbye.ulaw'
(language 'en')
? ?-- Timeout on SIP/2063161626-00000002, going to 't'
? ?-- Executing [t at conference-calls:1]
Playback("SIP/2063161626-00000002", "vm-goodbye") in new
stack
? ?-- <SIP/2063161626-00000002> Playing 'vm-goodbye.ulaw'
(language 'en')
? ?-- Executing [t at conference-calls:2]
Hangup("SIP/2063161626-00000001", "") in new stack
?== Spawn extension (conference-calls, t, 2) exited non-zero on
'SIP/2063161626-00000001'
? ?-- Executing [t at conference-calls:2]
Hangup("SIP/2063161626-00000002", "") in new stack
?== Spawn extension (conference-calls, t, 2) exited non-zero on
'SIP/2063161626-00000002'

Has anyone else encountered this problem before? I saw one posting on
the listserv, but it said to add in the pcm lib and I did that and no
change.

Help.

Thanks a bunch,

Joe