If we're a assuming this is implemented by the OS, then a different OS. If implemented by a carrier, then I'd obfuscate my data through a VPN and possibly other tools. I'm already on a different OS and VPN so not much would change.

e: I guess a vpn wouldn't work if this was implemented by a carrier, but neither would a flipphone. At any rate, since the privacy community keeps coming out with tools, it would be a matter of time before a new workaround came out.