Dynamic DNS

One problem I just thought of is roaming on the mesh. I have a SIP app on my phone, and I'd like to be able to call others no matter where I am on the mesh. Now outgoing, this works fine. But incoming, it's hard to keep track of what IP to dial (I know you could use a PBX but 1. that's a central point of failure and 2. this is only one example of the potential usage for this). I was thinking we could have a sort of dynamic DNS system where mesh services could roam. I can think of three ways this could work:

1. AREDN could be set up to not advertise services for disconnected devices (which IMHO should happen anyway) and you could set the service up on each mesh node so it was advertised on whichever node the phone was connected to
2. There could be an API of some sort where an HTTP request would enable the service on the new node (it would somehow have to disable it on the previous node). Perhaps a phone app and computer client could keep track and report?
3. There could be a "roaming" option on a service that caused it to propagate automatically to all other nodes and the user specifies a MAC address rather than an IP. Combine this with the disabling advertisements for disconnected devices and that creates an ideal roaming situation.

Would any of these be possible? I think the third one would be the best as it is automatic and requires no client software.