The Cisco 6-port Voice/Fax Expansion Module provides enterprises, managed service providers and service providers the ability to directly connect public-switched telephone networks (PSTNs) and existing telephony equipment to Cisco 2821, Cisco 2851, Cisco 3825, and Cisco 3845 integrated services routers. With support for up to 24 total voice and fax sessions, the Cisco 6-port Voice/Fax Expansion Module is ideal for networks with high analog (foreign exchange office [FXO]).