[Asterisk-Users] hangup()???

[Altus Snyman]

Good day all
I want to tell asterisk that it should hangup a channel in a certain step
For example:
exten => s,5,Dial(SIP/302,25)
exten => s,6,Hangup
exten => s,7,Hangup(SIP/302)

What happens is that if someone calls into the pbx and hangs up before 
it gets answered it still keeps on ringing on the internal side and if 
you pick up there is nothing
Please Help