Cisco phone 7945G called end problem still flashing and aler

dear all

i have some cisco 7945 phones when i call one extension to another and it rings after 3 or 4 seconds when i end call still the call is alerting on the incoming phone and i have to forcely end the call its not doning that automaticly can somebody help me what should i do to slove this problem i dont know what is happening to the phones i have some soft phone which installed in my computer and they work fine and i end the call the calls ends at both party but the cisco phones 7945 does not

also when i dial the number it takes 4 to 5 seconds to dial a number.