Dial Pattern Help use 7 instead of 9 for outside trunk

Good day,

I am hoping someone might be able to assist me
with changing the dial pattern from using 9 to access
an outside truck to 7.

Reason is I have a handful of users with sticky fingers and
they call 911 by mistake.

Currently my dial plan has this layout
911
011.
1NXXNXXXXXX
9|.
NXXNXXXXXX
NXXXXXX

When I try to change 9|. to 7|. or any other number I get a call can not be completed message. Only 9 seems to work.

Any help or other ideas / options would be great.