CCNA VOICE Phone keeps rining

Hey, guys i'm prepping for my exams and got flowroute on my cisco 2801.
Everytime i call from a external number and hang up the phone continues to ring how can i make that stop?
Everytime i call from a external number and hang up the phone continues to ring how can i make that stop?
Comments
Make sure you see the CANCEL request being both received, and sent. Should end with a message something like this "SIP/2.0 487 Request Cancelled"
Thanks for the replay useful information. when i call for 5 secs and hang up phone continues to ring for a long time. So i went ahead and put a timeouts ringing <value> so it doesn't ring forever. but it still rings through out the timeouts even though i click 5 secs.
in the debug messages i got the
180 Ringing
when i hang up it received a cancel
then it says
500 Internal server error
480 Temporarily Not available
Do you have a firewall inline? Keep an eye on the logs to make sure that it’s not dropping/filtering your SiP traffic.
Which IOS are you running?
I'm not running no voice ios which can maybe be one of my problems. I'm currently running if i'm not mistaken since i'm not home it's c2801-adventerprisek9-mz.124-20.T3.bin