To clarify, this purely for dial up connections, no PC/ActiveSync, e.g. CF modem and Bluetooth GPRS dial up. Power settings cannot be used because the PDA does other things that it cannot do when switched off. I never thought the phone lines reliable enough for a 13 hour connection.
Guess there isn't much demand for something like this because few people use dial up on PDAs. I'll happily pay for this software, it doesn't have to be freeware.