There are several ways this can be dealt with depending on the level of security you require. A simple push button can be fitted on the outside and inside of the gates, these can be controlled by a timer which disables them during certain times and day if required. The same can be done with Induction loops buried under the drive, these detect the metal mass of a vehicle approaching and trigger the gates.
There are also various intercoms that can work in tandem with all the other systems, so when someone arrives out of hours they simply push the call button and call the house, you can then speak to them and trigger the gate open if you want to allow them in. ( This can also be timed out at night if you are concerned about prank calls.)
The Latest GSM Intercoms use the mobile phone network to call your house phones from the gate, and can even divert automatically to your mobile phone and you can let them in, even if you are not at home. They would then normally leave via an induction loop detector on the inside when they approach the gates on the way out.
Of course your remote controls (Zappers) will work along side all of the various access controls, so the options above are really just to take care of visitors and deliveries.