The sad reality is that POTS is dying. The upside of this is that in principle we don’t need a VOIP provider, right? We should be able to run our own SIP server and place a call to another SIP user without using a POTS line -- thus w/out a subscription to a service. SIP addresses look like email addresses.

The problem is, IIUC, I have no way of knowing the SIP address for my bank. I only have their phone number. Is there a way around this? Is there a way to obtain the underlying VOIP address for a phone number?