I have had this problem in New Zealand where signal strength is low. That is the
“[WIP] No more ctx, call adl_gprsUnsubscribe()” error while activating a bearer. Any repeated attempts would also fail. The only solution I had was to reset (at+cfun=1) I have never liked such a drastic solution.
I have found that the problem occurs after a long period of inactivity (3-4hrs). I find now that instead of the total reset the same can be achieved by de-register (AT+COPS=2) re-register (AT+COPS=0).
I have an application which uploads every 6hrs, if the first attempt fails apply above and bearer activation happens straight off.(it seems with a much reduced time lag)