The voice module is not recognized by the router during a new install, or after a Cisco IOS Software change.
To ensure that the module is supported on your platform, refer to the Voice Hardware Compatibility Matrix (Cisco 175x, 1760, 2600, 3600, 3700, VG200, Catalyst 4000, Catalyst 6000).
To ensure that the router is running a Cisco IOS Software Release that supports the module, refer to the Software Support for Hardware section of the Software Advisor.
Pay close attention to the release train. For example, if Cisco IOS Software Release 12.2(2)T is the minimum image, the Cisco IOS Software Release that is used should be part of the "T" train.
Check the Cisco IOS Software feature set by looking for the image file name in the output of the show version command, as follows:
R14#show versionCisco Internetwork Operating System SoftwareIOS (tm) C2600 Software (C2600-IS-M), Version 12.0(7)T, RELEASE SOFTWARE (fc2)Copyright (c) 1986-1999 by Cisco Systems, Inc.Compiled Tue 07-Dec-99 02:21 by phanguyeImage text-base: 0x80008088, data-base: 0x80C524F8ROM: System Bootstrap, Version 11.3(2)XA4, RELEASE SOFTWARE (fc1)R14 uptime is 2 weeks, 2 days, 4 hours, 43 minutesSystem returned to ROM by power-on at 13:09:31 test Sun Jun 1 2003System image file is "flash:c2600-is-mz.120-7.T.bin"Cisco 2621 (MPC860) processor (revision 0x101) with 26624K/6144K bytes of memory.Processor board ID JAB041307K5 (4136116510)M860 processor: part number 0, mask 49Bridging software.X.25 software, Version 220.127.116.11 FastEthernet/IEEE 802.3 interface(s)1 Serial network interface(s)2 Serial(sync/async) network interface(s)2 Voice FXS interface(s)32K bytes of non-volatile configuration memory.8192K bytes of processor board System flash (Read/Write)Configuration register is 0x2102
Voice modules usually require a Plus version of Cisco IOS Software. Based on the image file name, determine the current feature set by referring to the Cisco Feature Navigator.