AT&T Inc. (AT&T) is a communications holding company. Its subsidiaries and affiliates, AT&T operating companies, are the providers of AT&T services in the United States and around the world. Their offerings include Internet protocol (IP)-based business communications services, third generation (3G) network and wireless coverage worldwide, and Internet access and voice services. Its offerings also include directory publishing and advertising sales of its Yellow Pages and YELLOWPAGES.COM organizations. The Company operates in four business segments: wireless, wireline, advertising solutions and other. In September 2009, the Company acquired Plusmo, Inc., a provider of cross-platform mobile application solutions. In October 2009, the Company announced the acquisition of VeriSign's global security consulting business. In November 2009, the Company completed its acquisition of Centennial Communications Corp.