Hi,
Within the main menu Add a new Touch Tone the green cross.
Make the Sequence the a series of question marks that are identicle to the number of digits within your business extension numbers. For example we use 300 so within the sequence enter ???.
Then create either an assisted or transfer node, within the Specific Tab, go to System Defined Variables and select "$KEY".
This will then allow a caller to enter an extension number directly from the first menu.
Hope this helps,
JPR