asterisk users - Mar 2005 - Zap keeps online if caller hangs up

It just bothers me ;-)

If somebody calls me via PSTN / TDM422 card and hang up, than my phones 
still rings!
What do I need to change for that?


exten => s,1,NoOp,${CALLERIDNUM}-${CALLERIDNAME}
exten => s,2,Answer
exten => s,3,zapateller  ; torture telemarketers
exten => s,4,Background(custom/Welcome-to-ELMIT) ; tell them who you are
exten => s,5,Background(if-u-know-ext-dial)
exten => s,6,SayUnixTime
exten => s,7,Dial(${PHONE_601}&${PHONE_621}&${PHONE_603},30,tr)  ;
ring
phone_601, 621 & 603 for 30 seconds
exten => s,8,VoiceMail(u601)  ; if no one answers send to
exten => s,109,VoiceMail(b601)  ; if busy send to voicemail
exten => s,110,Hangup