With IPHost Network Monitor you can run simple snmp requests against a Nortel device in your network.
x25DteLcnCallingAddress
x25 Dte Logical Channel Number Calling Address
1.3.6.1.4.1.562.2.4.1.90.4.12.1.5
This attribute indicates the calling X.25 address from which the call originated
Back to Nortel-Magellan-Passport-X25DteMIB MIB page.
IPHost Network monitor allows you to monitor x25DteLcnCallingAddress 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.