asterisk users - Jan 2004 - DTMF via SIP not working for certain phone systems

I really hope that someone can help me with this one.

DTMF tones are not working for certain places that I call, specifically
1-800-882-8880 which is the AA advantage line.  It works for almost
everyplace else.  If I bypass asterisk, the call works fine.

Network looks like:

<SPA-2000> --SIP-- ASTERISK --SIP-- <AS5350> --PRI-- PSTN

sip.conf entries

[VGW01] (this is the AS5350)
type=friend
nat=no
host=192.168.0.1
context=default

[8475551212] (this is the SPA-2000)
type=friend
secret=XXXXXX
nat=yes
host=dynamic
canreinvite=no
qualify=yes
mailbox=8475551212
context=unlimited

SPA-2000 is using INFO
AS5350 is using dtmf-relay rtp-nte

Everything is using G711u.  I have also tried setting the whole system
to inband including the sip.conf entries.

The weird part is that if I watch the network traffic, I don't see the
SIP INFO messages for the dtmf when I'm connected to the number listed
above.  Normally, I do.

I have also tried this with an ATA-186 with the same results.

Any suggestions would be very appreciated.

Stephen