Delayed dialing is a technique that lets you enter (and edit) a phone number you wish to call without dialing 'live'. Instead of picking up the receiver first, leave it in the cradle then dial as normal.
This allows you to see the number fully without actually dialing it, thus helping to prevent wrong numbers or accidentally dialing 911. You can edit the number by hitting the << keys, allowing you to correct mistakes quickly.
Delayed dialing also allows you to quickly redial external numbers. If you begin to enter a number that you've called recently, your Cisco phone will 'remember' these numbers, as well as the prefix to dial out. Just use the navigation buttons on your phone to select the number you wish to redial.
When your number is entered fully and correctly, simply pick up the receiver to initiate the call. If you want to use the speaker function, leave the receiver in the cradle and use the 'Dial' button to launch the call.