The IP Communications High-Density Digital Voice/Fax Network Modules are an addition to the Cisco Systems IP Communications suite of solutions. The IP Communications High-Density Digital Voice/Fax Network Modules deliver high-density digital voice connectivity, high-density WAN connectivity, analog voice connectivity, and conferencing and transcoding capability in a network module form factor.The network modules provide enterprises, managed service providers, and service providers with the ability to directly connect the public switched telephone network (PSTN), traditional telephony equipment (such as private branch exchange (PBX), key systems, analog telephones, and fax machines), and WAN to Cisco® 2811, 2821, 2851, 2911, 2921, 2951, 3825, 3845 and 3925, 3945 Unified Communications Routers for either IP Communications capabilities or pure toll bypass. The IP ommunications High-Density Digital Voice/Fax Network Modules flexibly operates within two different Cisco Unified Communications (UC) environments—the Cisco Unified Communications Manager (UCM) system with Survivable Remote Site Telephony (SRST) or Cisco Unified Communications Manager Express (UCME).The network modules can be integrated with these IP Telephony solutions in a Unified Communications Router, to provide a complete IP Communications solution for full service branch customers.