Why would you need additional numbers? 

Many companies or marketers want to track where their calls are coming from. If you have dozens of marketing campaigns happening at one time you can not accurately gauge their performance if the calls are going to one number. It is a good idea to use different numbers for different landing pages, local ads, search engine marketing, social media, email marketing or other special promotions.

Also, most companies want a local and a toll free number (It just looks better). Many of our customers also run different companies and need separate numbers.