If you’re using the Cisco SPA series phones they are similar to using other IP phones.  The easiest way to think of using these phones is the way you use your cell phone.  You can dial and interact with the phone before you pickup the handset or go off-hook to use the speaker phone.

Dial a number and then press ‘Dial’ or go off-hook.  You can use an IP phone the traditional way where you would pickup the handset and then dial but there are sometimes confusing delays when dialing a phone number that way.

If the phone has a display you will see a row of soft-key along the bottom row of the display and they will change according to the features you will have available to you depending on the state of the phone.  For example the options the soft-keys will show will be different if you are on a call or not on a call.  They will also be different if you are waiting to transfer a call.