The Cisco ATA 191 Multiplatform Analog Telephone Adapter turns traditional telephone, fax, and overhead paging communications devices into IP devices for greater cost-effectiveness. Customers can take advantage of IP telephony applications by connecting their analog devices to Cisco analog telephone adapters. The ATA 191 is the preferred solution to address the needs of customers who connect to enterprise networks, small offices, or unified communications as a service from the cloud. It has two standard FXS ports, which can be configured independently as two Session Initiation Protocol (SIP) registrations. With the ATA 191, customers can protect and extend their existing investment in analog systems, as well as smooth their migration to pure voice over IP in a more affordable and reliable way. The ATA 191 is designed to work with third-party call control systems and does not work with Cisco call control systems.