From your SMDR record it looks like all the mitel is receiving is "60". What you might want to try just for kicks is creating a 2 digit extentsion or hunt group and calling it from the nortel. See if the call routes properly then. depending on what you have set up in the nortel, you may have to still dial a 4 digit number in order for it to complete. It looks as though the nortel is stripping too many digits off of the string.

Since you have switched to PRI on the 200, you can connect a serial cable to the card at 38400 with a terminal program. Enter the following commands:
option +dispcall
option +cause

This will let you view cause codes and other information about the call including some caller ID. You will not see the name becuase of how NI2 works.

This is based on an assumption that this is a PRI card.

Simon