Intralata is just another name for local toll calls or regional calls. These calls are made to numbers outside your local calling area but before your long distance. These are usually carried by your local phone company, unless you have a long distance service that could supply local toll calls. You have an option of retaining your local toll calls with your local phone company or pass it through your long distance carrier.
You should also be aware that there are cheap long distance carriers that offer local toll calls, sometimes at rates much lower than those offered by your local phone company.
Click here to view the difference between interstate and intrastate long distance.