We have a few POTS adapters in use and recently converted a long-time landline user to a POTS line (the POTS line was costing them nearly US$175/mo!). Everything works except for call waiting.
We get the call waiting tone (though it’s a bit funky), but when the user presses the Flash button, the call on the original circuit disconnects. I tried this on an old school phone the old school way (‘hang up’ the phone for 1 second, let go, and it flips over to the other line), and it works fine.
Has anyone had a [portable] phone with a Flash button that causes the original caller to be disconnected when moving to the call waiting?