The Cisco IP Communications voice/fax network module for the Cisco 2600XM Series, Cisco 2691, and Cisco 3600 and 3700 series voice gateway routers enable packet voice technologies including VoIP (H.323, Media Gateway Control Protocol (MGCP), and Session Initiation Protocol (SIP)), voice over Frame Relay, and voice over ATM (ATM Adaptation Layer 2 (AAL2) and AAL5). Supports up to four channels of analog/BRI voice using any supported coder-decoder (codec). (No support for T1/E1 or data WAN.)