With IPHost Network Monitor you can run simple snmp requests against a Nortel device in your network.
x25DtePleEncAddrToX25LkupFlrs
x25 Dte Ple Enc Address To X25 Lkup Flrs
1.3.6.1.4.1.562.2.4.1.90.6.11.1.1
This attribute indicates the number of times a translation attempt from an Encapsulation address to an X.25 address failed to find a corresponding X.25 address. Such a failure could occur when a Protocol Port, linked to a RemoteGroup via the linkToProtocolPort attribute of the RemoteGroup, requests through the software that a X.25 call be established to a particular Encapsulation address. If the RemoteGroup does not have a Peer component linked in its linkToPeer attribute list, with the encAddress attribute equal to the Encapsulation address specified, this counter will be incremented, because the corresponding Peer component needed to establish an X.25 connection was not found.
Back to Nortel-Magellan-Passport-X25DteMIB MIB page.
IPHost Network monitor allows you to monitor x25DtePleEncAddrToX25LkupFlrs 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.