anybody ever encounter this annoying issue with ios4 when you keep getting 'call failed' constantly until you either reboot, turn 3g off, turn on and off airplane mode? i am able to receive calls when this happens but its annoying that i have reset everytime when it happens. i notice it happens about the same time after i get off work when i get home. i know i can send and receive text. it happened to my roommate as well. we are running iphone 3gs under ios4.