The phone jack as shown has all the jacks wired in parallel. The M1DBH has the power leads wired in parallel, but the RS-485 data bus wires are in series.
An ideally configured RS-485 circuit has one twisted pair cable that runs past all the devices. The two devices at the farthest points of the circuit have terminating resistors installed; none of the other devices has a terminating resistor. The resistors prevent the signals from echoing back and forth across the length of the bus. Each device is connected to the twisted pair data pair by an (ideally) infinitly short cable/connector. The M1DBH maintains this ideal configuration by sending the data pair out to each device and then bringing it back to the same jack on a different pair. The printed circuit takes the data bus pair to the next jack where this is repeated until you get to the terminating resistor after the last jack in use. The phone gadget wires each device in parallel, and you end up with each device on a separate node. How will you decide which two are at the ends of the bus electrically so you know which get the terminating resistors? Plugging the terminating resistor into the gadget isn't going to stop the reflections. Besides, the charactaristic impedance of the bus is nowhere near spec with the parallel data bus wiring.
I suggest the better poor man's solution is to skip the hub and wire the devices as on page 12 of the M1G manual. You may get away with the incorrect configuration of the cheapo phone jack for some time, but Murphy's Law will catch up with you some day. It will probably be at the most inconvenient time, too.
Question: Isn't the poor man better off selecting a system a bit down scale from the ELK and then configuring it correctly rather than skimping on a premium ELK system? This seems a bit like saying VW Beatle tires work just fine on a Porsche 911S.
Regards. . . .John