There is no one-size-fits-all answer to this question, as the best phone system for a small business depends on the specific needs and budget of the business in question. However, some of the best small business phone systems on the market include the Avaya IP Office, the Cisco Unified Communications Manager, and the NEC Univerge SV9100. These systems offer a variety of features and benefits that can be tailored to the needs of small businesses, and they are all reasonably priced.