asterisk users - Jul 2005 - Sipura 3000 x special dialling pattern (pin code)

I need to place a call using a "pin code". To access an external line,
the host PBX (a Ericsson MD-110) will require that I dial 
*72*pincode#phone_number to complete any (trunk) call.

When I send the number, my Sipura 3000 will reject the call with 
"Forbidden - wrong password on authentication for INVITE" (see below).
All other calls sent to the Sipura box without the "weird" pattern are
OK.

Any ideas?

=== PIN CODE ==
     -- Executing NoOp("SIP/1022-f773", "Call to PSTN - PIN
CODE") in
new stack
     -- Executing Dial("SIP/1022-f773", 
"SIP/*72*9999999#0018885555555@pstn-spa3k|90") in new stack
     -- Called *72*9999999#0018885555555@pstn-spa3k
Jul 20 17:02:52 WARNING[7979]: chan_sip.c:6846 handle_response: 
Forbidden - wrong password on authentication for INVITE to '"Line
2"
<sip:asterisk@10.50.0.2>;tag=as4da311dc'
     -- SIP/pstn-spa3k-61d5 is circuit-busy
   == Everyone is busy/congested at this time
     -- Executing Busy("SIP/1022-f773", "") in new stack
   == Spawn extension (from-sip, 0018885555555, 103) exited non-zero on 
'SIP/1022-f773'
     -- Got SIP response 481 "Call Leg/Transaction Does Not Exist"
back
from 10.50.0.20

=== REGULAR CALL ==
     -- Executing NoOp("SIP/1022-0568", "Call to PSTN number 5359
-
pt9QAnP8") in new stack
     -- Executing Dial("SIP/1022-0568",
"SIP/5359@pstn-spa3k|60|") in
new stack
     -- Called 5359@pstn-spa3k
     -- SIP/pstn-spa3k-d03e is ringing
     -- SIP/pstn-spa3k-d03e answered SIP/1022-0568
     -- Attempting native bridge of SIP/1022-0568 and SIP/pstn-spa3k-d03e
   == Spawn extension (from-sip, 5359, 2) exited non-zero on 
'SIP/1022-0568'