Is it okay to charge one's cellphone with it turned on? The manual says the cellphone should be turned off when charging. So, will it charge even if it's turned on? And if you charge it with it turned on, can you receive calls?
You can charge any phone when it is on, but if the battery is totally down the phone may go back into charging mode. My Palm Pre, a battery pig, shows a battery charging symbol when the battery is down too low to run the phone. My GSM phones (2 Nokia and a Motorola) will run with a dead battery from the charger. Car chargers may support this mode where the plug in (AC) may not. The phone will definitely ring if it is on. I have made and received calls in this mode. The risk is a dropped call if the talk power takes too much power from the charger and the battery. Remember the charging times are all quoted with the phone off, so charging times when on may be much longer. This is not a big deal if plugged into AC outlet overnight, but if the battery is dead and you want to make a call in a half hour charging with power off is better.
I've been doing that since my second phone. The first one in 1984 had a base installed in the car, so when mounted to the base it was receiving vehicle power. That educated me the same was as the Cingular rep was educated. Why not be on "ship's" power whenever possible?