Today many people will look up your website before contacting you by phone or email. A website allows your customers to anonymously find out about the services you offer, without taking your time, or asking potentially embassing "stupid questions". Think of your website as another staff member - one that doesn't need sick days!
A website is also a great way for people to find your address and phone number to get in touch. Many people will search for you in google before using the phone book.