Cinterion plugin - unsupported ^SIND="simstatus"

[Colin Helliwell]

The Cinterion plugin tries 'AT^SIND="simstatus",2' in after_sim_unlock(). I have two Cinterion modems, neither of which - according to their AT Command Set spec - support the simstatus indicator on this command, and so instead return "+CME ERROR: 21" (invalid index).
Nonetheless, the operation continues with all 15 of its retries. Should there perhaps be a 'if (!response)' trap in simstatus_check_ready() so that it bombs out?
I ask for comment, since I'm not sure (a) exactly what the retries are waiting for; and, in particular (b) what the response would be while its waiting. (I don't have a modem which does support the indicator).