I am trying to find out who owns a RingCentral number that is being used by one of our clients. The number was set up under the previous provider for this client, but that provider is no longer in business. I do not do anything with development. Who could I contact to start an investigation to track down who this belongs to? What information would I possibly need to provide, as I don't have much to go on except the number and who is currently using it.

Ultimately I would like to move it to the customer's account.