A hypothetical VoIP service doesn't resell line numbers from bandwidth.com or one of its competitors that do nothing but provide line numbers at needed rate centers. Instead, the VoIP company obtains its own pool of line numbers and an adequate physical presence at various telephone company central offices and participates in number portability following existing telco rate center polygons.
A few of its subscribers become dissatisfied with the service, subscribe to a competing service that participates in number portability and port their numbers to the competitor.
What happens when the VoIP service goes out of business? I assume that they lose the line number pool and that existing subscribers lose service if no other company bought the subscriber base from the bankruptcy trustee.
What happens to the ported numbers? Is routing to the pool simply shut down? I assume that there is no obligation by the incumbent telephone company to switch those virtual lines.
Or do the ported line numbers continue to exist on the equipment of the phone companies they were ported to? In that case, how is routing handled?
The freed-up pool of unassigned line numbers is now available for assignment to whatever carrier needs it at any rate center in the area code. It won't necessarily be re-assigned to another carrier in the existing rate center, nor should it be if there's no need for it.