You won't be able to use AutoCal, as your transceiver is transmitting with an offset greater than 500Hz. You have to manually offset the openSPOT4's modem RX and TX frequencies with larger than 500Hz values.
Example: keep your transceiver at 433.900MHz the whole time
Try an echo test with the following RX/TX frequencies in the openSPOT4: 433899400, 433899300, 433899200, 433899100, 433899000. Also try the other way: 433900600, 433900700, 433900800, 433900900
Use the frequency which gives you the lowest BER (best voice quality) with your transceiver.