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.

The Cisco High-Density Analog and Digital Extension Module for Voice and Fax (EVM-HD) is an industry-leading voice and fax interface module for Cisco 2821, 2851, 2901, 2911, 2921, 2951, 3825, 3845, 3925, 3925E, 3945 and 3945E Integrated Services Routers. It helps enable packet voice technologies with support for voice over IP (VoIP), including H.323, Media Gateway Control Protocol (MGCP) and Session Initiation Protocol (SIP). The Cisco High-Density Extension Module allows Cisco 2821, 2851, 2901, 2911, 2921, 2951, 3825, 3845, 3925, 3925E, 3945 and 3945E Integrated Services Routers to connect directly to the PSTN and existing telephony equipment (for example, private branch exchange (PBX), Key system, analog telephones, and analog fax machines) through standard analog (FXS, DID, and FXO) and digital (BRI) interfaces. The High-Density Extension Module supports telephony toll bypass, new packet telephony applications, and full gateway integration. With support for up to 24 total voice and fax sessions, the Cisco High-Density Extension Module is ideal for networks with high analog and BRI call-capacity requirements;

The Cisco High-Density Extension Module includes the following components:

An 8-port extension module (part number EVM-HD-8FXS/DID)-Baseboard with 8 ports that can be configured individually for FXS or DID signaling

Voice and fax expansion modules:

– A 4-port expansion module supporting BRI (NT and TE) (part number EM-4BRI-NT/TE)

– An 8-port expansion module supporting FXS and DID (part number EM3-HDA-8FXS/DID)

– A 6-port expansion module supporting FXO (part number EM-HDA-6FXO)

– A 7-port expansion module with 3 FXS and 4 FXO ports (part number EM-HDA-3FXS/4FXO)
Adding expansion modules to the Cisco High-Density Extension Module baseboard increases voice and fax session capacity. The modular design of the Cisco High-Density Extension Module provides maximum flexibility-plug in up to two expansion modules in any combination to build the Cisco High-Density Extension Module best suited for specific packet telephony network locations.

The Cisco High-Density Extension Module provides gateway services for Cisco Unified Communications using Cisco Unified Communications Manager with Survivable Remote Site Telephony (SRST) or Cisco Unified Communications Manager Express (UCME). Gateway services allow users to deploy networks that take advantage of investments in existing legacy telephony equipment while also deploying and integrating IP telephony. The network can operate at any point on the voice, video and integrated data spectrum-with the ability to add connections for both traditional telephony devices and IP telephony endpoints.