Fixed: Can't call from T-Mobile G1(Google phone)

Phonomeon: When I try to make a phone call to any phone number by both of dialing or choosing from address book, after showing now-calling dialog for very short term(less than 2 seconds) it shows call ended dialog. I can answer incoming call, connect to internet services android normally offers.
Other condition: Last time I could make a call successfully was a couple of days ago and after that I didn't make a call from this phone.
Solution: Reboot the phone by using power button(red key that has the image of a phone)