What happens if a Hosted Messaging number ports to another provider?

If a Hosted Messaging number changes voice providers, it's likely that the new voice provider will attempt to overwrite the messaging as part of the voice port. It'll be up to the customer and their end-user to determine the appropriate course of action as far as keeping the messaging with Bandwidth. 

Please note, a number porting away to another provider could result in the messaging being disrupted as the new provider assumes ownership of the messaging route(s).