Phoenix-based Telesphere, a provider of business phone and Internet services, said today that it has agreed to acquire the VoIP business of Denver-based Unity Business Networks. Financial terms of the buy were not disclosed. Unity provides VoIP in Denver, Portland, and Minneapolis/St. Paul. Telesphere said it will market the services of both firms under the Telesphere brand. Telesphere is backed by Rally Capital, Hawkeye Investments, and the Greenspun Corporation.