This one-person startup that sells pizza is so profitable, the founder has hired over 100 people in less than a year with hardly any investors

Ilir Sela's friends and family learned to get used to his ring tone. When it went off, they knew they had to quiet down and turn off the music so Sela could take care of business. 

That business was turning an online pizza order into a real-life delivery to someone's home. Sela was doing it manually: He'd get an email with an order and call it in himself. 

"I remember going to switch from Verizon to AT&T, because AT&T allowed you to browse the internet and take phone calls at the same time," Sela told Business Insider. "At the time, I was getting orders once every few hours. I didn’t have a staff to transmit the order, I didn’t even have the technology to transmit the order."

Read the full article at Business Insider.