Hi there,
This feature is shown as supported with CUCM 9.x with the install of the latest Device pack;
Features Available with Latest Cisco Unified Communications Manager Device Pack
The following features require the installation of a Cisco Unified Communications Manager device pack containing the Cisco IP Phone configuration files. The device pack installs the firmware and the configuration files needed to enable the features. These features can be configured and may be turned off by default. After being turned on, these features may also have attributes or settings that can be configured. See the sections below for more details.
For information on the availability of Cisco Unified Communications Manager Device Packs, see:
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/compat/devpack_comp_mtx.html
Minimum Ring Volume
The Minimum Ring Volume feature supports a minimum ringer volume level for IP Phones.
Administrators can set a minimum ringer volume level that can range from 0 to 14. The default is 0 (silent).
Users can only adjust the ringer volume to a level greater than the configured minimum ringer volume value.
The feature is supported on the following Cisco Unified IP Phones (SCCP and SIP):
- Cisco Unified IP Phone 6921
- Cisco Unified IP Phone 6941
- Cisco Unified IP Phone 6945
- Cisco Unified IP Phone 6961
From;
http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cuipph/6900_series/firmware/933/release_notes/P069_BK_R9A78776_00_rn-9_3_3-6900-series/P069_BK_R9A78776_00_rn-9_3_3-6900-series_chapter_00.html#P690_TP_M20C59F2_00
You could try the latest Device Pack for CUCM 8.6 which is;
cmterm-devicepack8.6.2.25132-1.cop.sgn
Cheers!
Rob
