Hello,
Take a look on the SRND to understand the concept.
http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/srnd/collab10/collab10/preface.html
The CUCM supply the dial tone for the IP Phones registered on the cluster.
The router will be the interface with the PSTN.
Partition, CSS translations and other informations you will find at the SRND.
Regards
Leonardo Santana
Regards
Leonardo Santana
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