asterisk users - Nov 2007 - Grandstream 488 and DTMF with a call file

I have a grandstream 488 using FXO port. With asterisk 1.2.23
When I have DTMF mode set to RFC2833 (asterisk and grandstream) and I 
use a call file and AGI to
originate the call I dont get the DTMF tones on the device.

If I do it manually from a polycom 550 (set for RFC2833) it works.

When I change the DTMF mode to inband on both asterisk and grandstream 
and use
the call file it now works.

If I now use the polycom 550 (still set for RFC2833) and manually call
this does not work anymore - the grandstream is still set to inband now.

What kind of issue am I having?

Thanks,

Jerry