Hi,
I assume the "switch" are located in same location ?
You need to establish "connection" within "switch" location ( i will name it HQ ).
Add necessary route in 1721 and 800 route. Both sites of routers have to know how to pass the packet (route) when they want to reach the subnet (192.54.6.12 & 192.54.1.250)
Rgds,
Christopher