EX60 does not come with Multisite option so in this case you need to use the conferencing resources added in the MRGL on CUCM for these endpoints, which would be MCU for video conferencing.
Thank you for your reply, I already talked to Cisco support, they confirm me that no need to add MCU as I already have CUCM and Voice Gateway router, so no need to add MCU the Gateway will handle the conferencing for the 3 endpoints.
Please be aware of the following limitation if you plan to use and PVDM3 from ISR G2's for video conferencing
The EX60 does not support Multisite, neither do the DX80s, so you will need to have a MCU/TelePresence Server/Cisco Meeting Server/external bridge to host the conference if you wish to have all three connected.
Please remember to rate responses and to mark your question as answered if appropriate.