I'm not exactly sure what you mean by RIngCentral does not "cover" the Virgin Islands and Puerto Rico. If you have a U.S. toll free number from RingCentral, it is only provisioned for the U.S. and Canada. This being the case the Virgin Islands and Puerto are not able to call the toll free number.
However, they should be able to call any local number that you have on your RingCentral account without issue. Please let us know if this is the issue that you are having and we can look into creating a feature request to add the Puerto Rico and USVI to our toll free number provisioning.