asterisk users - Dec 2006 - Siedle DCA612-0 and Asterisk : problem with DTMF

I am trying to use the Siedle DCA612-0 porter interface
with Asterisk, I connected it to a Linksys SPA2100 ATA
and it seems to work correctly.
BUT
I have to send tones #61 to it in order to open the door
or a single tone 1 to 9 in order to talk to whoever is
at the door; it seems that tones are somewhat captured
by Asterisk when answering the calls and I have to press
at least 3 keys to get one through. Is there an option
where I can simply ask Asterisk to ignore every tone
sent during the call, not processing them, and simply pass
them through?
Thanks