It's smooth to connect to Telstra IoT network using Arduino MKR NB 1500 with fantastic Tesltra support.
We have observed a few problems.
(1) After MKR NB 1500 runs for a couple of hours, the modem may fail to work and it cannot connect to Internet any more, unless a cold restart (power off/on) imposed;
(2) At deep sleep mode, MKR NB 1500 still consumes around 1.5mA, which drains the battery heavily and is not good for long running sensors;
(3) The IoT network coverage is indeed bigger than mobile phone network coverage. MKR NB 1500 can still connect to IoT network at the place where my telstra phone has no reception, however the signal is marginal (RSSI around -100dB). The connection and data can get lost sometimes.