Some companies make the mistake of not considering their mobile version of the website until the main site is built. They may then find that many of the elements do not work as well on the mobile sites as they do on the desktop version.
You need to find out who your main audience is and what devices they are likely to be using. If you have a stats package on your website such as Google Analytics then you can see the devices that are being used to view your site. This will give you an idea of how much of your business is being impacted on by the mobile version of your site. You may be surprised as to how many people browse online through their phone or tablet even if its only as an initial look prior to using a desktop to make a purchase.
If your website is not very user friendly then you should consider creating a new one or updating your current one to allow more users to interactive with your site. If you want to offer a lot of functionality then you could create an App that will allow people to download it on to their phone or tablet.