Even better, the phone can just sleep and modem will wake it up when (SMS) messages/or calls are received. No need for polling. You can also set up RTC to wake

Even better, the phone can just sleep and modem will wake it up when (SMS) messages/or calls are received. No need for polling. You can also set up RTC to wake up the phone periodically and perform whatever polling you need and put it back to sleep afterwards, all automatically.