Polycom MGC Administrator Administrator's Manual page 539

A list of slots appears.
5. Click the slot containing the Net-T1/Net-E1 Network Interface module
(PRI48) to configure, or click the plus [+] icon next to the card icon, to
list its spans.
6. Right-click the unit whose ISDN line quality you want to check, and then
select:
Monitor 15 min to retrieve statistical data on the line quality in the last
15 minutes.
Monitor 24 hours to retrieve statistical data on the line quality in the last
24 hours (in 15 minute intervals).
MGC Administrator's Guide
C-5