Porting out and back in


I've been with Visible for a number of years now. In the course of their recent network upgrade, they really screwed me over. I've signed up for their new service and ordered a new sim card. But my old phone was not compatible with the new service, so I couldn't activate the new service. In the meantime, they shut down my old service and would not let me pay my bill beyond a certain date. I now have a new phone and would like to activate the new service, but the Visible app insists that this is not possible and the only thing to do is to sign up as a new member, and it will not let me chat with anyone other than with their braindead AI assistant. Inconvenience aside, I am willing to sign up as a new member, but would of course want to keep my old phone number. Apparently the "easy" way to do this is to port the old number out to another carrier and then port it back in. Inconvenience aside once again, I am willing to do that. But I have no intention of signing up for service with another carrier.

So my question is, has anyone does this? Is it possible to somehow port the number out and port it back in without establishing cell phone service with another carrier? I know about Google Voice, but I already have a free Google number and Google does not seem to allow having more than one number with them.

Thank you for any advice on this.