We currently have three branch offices in which we have Cisco 2811 Routers running 12.4(9)T and CME 4.0 (GUI 22.214.171.124). The 2811's utilize NM-HDA 4FXS/4FXO cards supplied with analog phone lines for local PSTN access and are connected to the main site via T1 through a single VWIC interface. We would like to reduce the number of analog lines in use by each branch (approximately 10 users per office) to two lines and have the second line provide single line voice/fax functionality by using FAX detection or something similar.
My question, is this possible given the current hardware installed at the sites? I have found documentation which described using an NM-HDV with voice interface cards on the 2600 and 3600 series routers, but nothing for the NM-HDA or the 2800 series. If there is another configuration solution I would love to hear about it and would greatly appreciate any configuration guides and/or examples you can provide.