Hotline service parameters will have to be configured to match what the far-end switch expects to receive during signaling.
The hotline service parameters must first be configured before configuring the hotline feature.
To configure the hotline service parameters, perform the following:
Navigate to the Service Parameters Configuration page (System | Service Parameters).
Specify the appropriate Server.
Under the Service drop-down menu, select Cisco CallManager.
Click Advanced.
Navigate down to the section Clusterwide Parameters (Route Class Signaling).
For Route Class Trunk Signaling Enabled select True from the drop-down menu:
Specify a text label for the SIP Hotline Voice Route Class Label field.
Specify a text label for SIP Hotline Data Route Class Label field.
Click on Save.