With IPHost Network Monitor you can run simple snmp requests against a Nortel device in your network.
x25DteHighestOLChannelNumber
x25 Dte Highest OL Channel Number
1.3.6.1.4.1.562.2.4.1.90.22.1.6
This attribute specifies the highest Lcn number of the One-way Outgoing Channel range for this X.25 interface. A value of 0 indicates that there are no channels in this range.
Back to Nortel-Magellan-Passport-X25DteMIB MIB page.
IPHost Network monitor allows you to monitor x25DteHighestOLChannelNumber 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.