asterisk users - Oct 2006 - Asterisk stopps matching extensions after first digit

Hi all,

I have problems receiving calls from PSTN with an Wildcard T207P.

All internal SIP devices have a 3 digit extension, e.g. 873. 

When I call the extension from the PSTN this way everything works fine:

1. enter the number on the phone
2. lift off the handset

But when I call it that way Asterisk stopps matching the extension after the
first extension digit (8 in that case):

1. lift off the handset
2. enter the number on the phone

Asterisk then says that the extension does not exist and that the call is
rejected.

The context for receiving incoming calls in extensions.conf looks like this

[zap-in]
exten => _999[8-9]XX,1,Goto(internal,${EXTEN:3},1)

Is it possible to tell asterisk that it should match only 3 digits
extensions and where can this be configured? (extensions.conf, zapata.conf
or anywhere else)

Thanks in advance

Regards, Jens