The world just isn't the same as it used to be. The yellow pages isn't used any more, and online directories aren't utilised nearly as much as they were just a few years ago. So, how do people find services? Just as I'm sure you do; if they want to find a particular service they will just pop online and search on Google (other search engines are available) - or they search for you directly. This is why you need to have a place online for them to land.
Not just any place, though. How many times have you visited a 'dated' website and thought, "Nah." and immediately left? Quite a few, I'd guess - I know I have.
You need a modern; responsive; great-looking and regularly maintained website, that keeps visitors engaged and makes them want to engage with you.