Hi Luis,
You can set Hold Reversion to disabled at the Cluster level (as shown below) and just set it at the Line/DN level for the required group of phones;
Configuring Call Reversion Timer Settings
Perform the following procedure to enable the hold reversion feature and to configure the hold reversion timer settings. This procedure assumes that DNs are configured for a phone or that the phones are using auto-registration.
Consider the following information when you are configuring call reversion timer settings:
•
To enable hold reversion for the cluster, change the Hold Reversion Duration timer in the Service Parameters window to a value greater than 0.
•If you do not want to use the default system setting for reminder alerts, configure the Hold Reversion Notification Interval timer in the Service Parameters window. The default value specifies 30 seconds.
•To disable hold reversion for a line when the system setting is enabled, enter a value of 0 for the Hold Reversion Duration timer in the Directory Number Configuration window. If you leave the field empty, Cisco Unified Communications Manager uses the cluster timer setting.
•To enable hold reversion for a line when the system setting is disabled, set the Hold Reversion Duration timer in the Directory Number Configuration window to a value greater than 0. To enable reminder alerts, configure the Hold Reversion Notification Interval timer to a value greater than 0 in the same window or leave it blank to use the cluster setting.
•To configure hold reversion timer settings that differ from the cluster settings when hold reversion is enabled, enter different values for the hold reversion timers in the Directory Number Configuration window.
Procedure
Step 1 Find the hold reversion timers for a line or the cluster:
•To enable hold reversion and configure timer settings for the cluster, choose System > Service Parameters in Cisco Unified Communications Manager Administration.
–From the Server drop-down list box, choose the server that is running the Cisco CallManager service.
–From the Service drop-down list box, select the Cisco CallManager service.
The Service Parameters Configuration window displays. Go to Step 2.
•To enable or disable hold reversion and configure hold reversion timer settings for a line, choose Device > Phone in Cisco Unified Communications Manager Administration. Click Find to display the device pools list, or use the search results from an active query.
–Choose a device from the phone list that displays in the Find and List Phones window. The Phone Configuration window displays.
–In the phone configuration window, choose a Directory Number from the list at the left.
The Directory Number Configuration window displays. Go to Step 2.
Step 2 Configure the hold reversion timers:
•In the Hold Reversion Duration (sec) field, enter a value greater than 0 to enable the hold reversion feature. To disable the hold reversion feature, enter a 0. You can enter a value from 0 to 1200 seconds (inclusive). This timer notifies a user when a held call enters the reverted state.
•If you do not want to use the existing setting for reminder alerts, enter a value between 0 to 1200 seconds (inclusive) in the Hold Reversion Notification Interval (sec) field. Cisco Unified Communications Manager uses this timer to schedule periodic reminder alerts to the phone of the holding party for reverted calls. If you enter a 0, no reminder alerts get sent.
Step 3 Click the Save button.
Step 4 Reset any devices to incorporate changes in the Directory Number Configuration window.
Step 5 Repeat this procedure to configure additional timers.
From;
http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/8_0_1/ccmfeat/fsgd-801-cm/fsholdrv.html#wp1090206
Cheers!
Rob
