We don't keep a call records by default in the 7100. You would have to set up via SMDR logs. We can export them externally to a syslog server or you can even store them locally on the 7100.
See here for more info: Configuring SMDR Reports for the NetVanta 7000 Series
Let me know if you have further questions.
You can monitor channels in use via SNMP and graph it with a network monitoring program such as MRTG, etc.