When not in bridged mode, the modem would show the external IP, with the 99.x.x.x IP address (at least in most of ontario I think)
(You can often still log into the modem via 192.168.100.1 on many modems, when its in bridged mode)
I just checked mine..
(which used to be in gateway mode, but is now in bridged mode)
In the modem status page, its showing a 7.x.x.x address now.
But when logging into my 3rd party router, it is showing my correct 99.x.x.x external address.
The 173 may be as with my 7.x address.
What does the 3rd party modem show as its WAN IP?
Rogers 9865, LG 47LV5400 LED TV, Onkyo HT-R690.