With all the Package Routers online almost all of the time and communicating with each other, they can signal forward to the next Router with information about the incoming Smart Case. This second Router acknowledges the connection and repeats the process until this virtual Smart Case is delivered. They do this using the Virtual Forwarding Log.
The Virtual Log is forwarded through the network until it reaches the target Inbox router which then sends it back to the originating Router of the Virtual Forwarding Log. The originating Router can then send it out again choosing different route a number of times then the best Virtual Route is chosen and the actual Smart Case is forwarded that direction.
If the Virtual Forwarding Log can not find a solution or predicts the case will take too long or be too expensive, etc. the sending user can be informed of possible delays or cost increases.
If a Router loses a data connection or can't find a delivery solution with the Virtual Forwarding Log it is still obliged to operate though with less efficiency. It simply sends out a request for a Pigeon and sends the case onwards to the next Router which in the Routing Table which is both within Pigeon range and closer to the target location. This process continues until all the Smart Cases in the Router have been sent on. It obviously stores a record of every Smart Case it has handled which it then submits to the Dispatch Service Provider once it is back online.
Top Image Public Domain: Tube Map 1908