When you have locales configured on CUCM for International characters SCCP signaling will take care of the intraclustern signaling. For Intercluster communications if the Unicode Character wants to be exchanged a SIP trunk is required. H323 will only support ASCII based Caller ID name.
Configure a Add a New Trunk
Create a Common Device configuration profile with the proper lenguage locale. In this example we use Russian Locale.
Under the trunk settings make sure to enable Transmit UTF-8 for Calling Party Name
Configure the rest of the SIP trunk as regular.
Under the Phone select the User locale to match the setting on the Common device configuration profile for the SIP trunk.
From a sniffer capture you should be able to see the SDP messages inside the INVITE and 200 OK.