Most likely it is your signaling. You have the tenor set to reverse battery, but are you 100% positive that your tellular is providing the reverse battery for answer? My guess is probably not. Try setting the signaling to plain loop start and then config the answer delay to 120. BTW, while you can configure signaling to reverse battery and supervision to disconnect and answer, only the reverse battery will be used. As detailed in the CLI guide, the supervision options will only work if signaling is set to loop start only or loop start with forward disconnect.