[Asterisk-Users] Dialplane slip

[Altus Snyman]

Good day all
My extensions.conf is something like this

[main]
;---incoming+ play welcome message
extens => s......
;---users extensions
exten => 100.....
;---outgoing
ignore 0
;-----------------

It all works fine
The message says dial 1 for this ens....
But if I dial 0+number it will actually make a outgoing call!
How do I stop this?
I must allow the ignore 0 for internal uses but not if a call comes in
from the outside?
Please Advice
Thanks
Altus