You can use something like Vitelity vMobile which routes your cell phone as an extension to a PBX system/SIP server. This gives you total and complete control o

You can use something like Vitelity vMobile which routes your cell phone as an extension to a PBX system/SIP server. This gives you total and complete control of what happens on incoming and outbound calls. For example, you could have your cell phone number give an IVR menu, ring forever, play hold music, you're only limited by your SIP server. This is the closest I've seen to providing your own dialtone. I used it for a while and the only con---and it is a major con for me---is that, like most innovative or unique MVNOs, it's riding on Sprint. And Sprint is really terrible, at least where I live, which made the service great, except that getting data to work often involved walking around in large circles til I was able to catch an LTE signal.