The Cisco® High-Density Analog and Digital Extension Module for Voice and Fax (EVM-HD) 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, 2851, 2901, 2911, 2921, 2951, 3825, 3845, 3925, 3925E, 3945 and 3945E Integrated Services Routers. With support for up to 24 total voice and fax sessions, the Cisco High-Density Extension Module is ideal for networks with high analog (foreign exchange station [FXS], direct inward dialing [DID], and foreign exchange office [FXO]) and digital (Basic Rate Interface [BRI]) call-capacity requirements.