It should be reasonably easy to spoof an outgoing phone number, your issue is with getting the reply. Imagine a parcel to send somewhere:
The sender address can be modified to be whatever you want it to be, however, the reply will then also go that address and not to your home address.

What you would need to do is manipulate the phone system to somehow associate your old phone number with any phone number you have access to. This is not only insanely difficult unless you already have a way into the phone system but also highly illegal.

If you have any option to sign up for a phone plan or prepaid SIM card with a desired phone number option that would be your easiest way. Maybe one of those services are helpful for you, but that was just the first hit on a quick search. No guarantee any of those will be useful.

Maybe this can help. Basically you’re looking to split your screen into virtual screens.

Don’t know if this will work on the fly though.

You could try just using the ping or host commands, they will also try to resolve the domain.

Also can you access the services by using IP:Port?