With IPHost Network Monitor you can run simple snmp requests against a Nortel device in your network.
x25DteLapbStateChanges
x25 Dte Lapb State Changes
1.3.6.1.4.1.562.2.4.1.90.5.13.1.1
This attribute counts the number of times LAPB state has changed. Refer to the attribute 'linkState' for the set of possible states.
Back to Nortel-Magellan-Passport-X25DteMIB MIB page.
IPHost Network monitor allows you to monitor x25DteLapbStateChanges on Allied Telesis device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Nortel modems right now.