the concept of the VXR router was introduced years ago, around 1999 or 2000.
the VXR indictated that the router had an incorporated MIX (multiservice interchange), to provide the capability to support voice applications. it provided for the ability to switch DS-0 timeslots between multichannel T1 or E1.
it also allows for the DS-0s to be switched through the 7200 without any processing.
please see the following link for some VXR info:
http://www.cisco.com/en/US/products/hw/routers/ps341/products_installation_guide_chapter09186a00801d0984.html#wp1014104
