Squeak sound and disconnection--on call

Hi…to all by the way im new to asterisk…currently im working in a call center implementing asterisk with vicidial as our dialler software…im having problem with squeak sound then disconnection…my logs on asterisk is this…

//127.0.0.1:4577/call_log--HVcauses--PRI-----NODEBUG-----19-----CONGESTION-","2008-07-26 02:20:24",“2008-07-26 02:20:29”,5,0,“FAILED”,“DOCUMENTATION”
"",“1006”,“916319729755”,“default”,""“Nellie”" <1006>",“SIP/1006-0962a2f0”,“SIP/VoIP-095ff540”,“DeadAGI”,“agi://127.0.0.1:4577/call_log–HVcauses–PRI-----NODEBUG-----19-----CONGESTION-”,“2008-07-26 02:20:41”,“2008-07-26 02:20:46”,5,0,“FAILED”,“DOCUMENTATION”
"",“1006”,“916319729755”,“default”,""“Nellie”" <1006>",“SIP/1006-09604a80”,“SIP/VoIP-09622560”,“DeadAGI”,“agi://127.0.0.1:4577/call_log–HVcauses–PRI-----NODEBUG-----16-----CONGESTION-”,“2008-07-26 02:20:44”,“2008-07-26 02:20:48”,4,0,“FAILED”,“DOCUMENTATION”
"",“1006”,“916319729755”,“default”,""“Nellie”" <1006>",“SIP/1006-0962a2f0”,“SIP/VoIP-b7900628”,“DeadAGI”,“agi://127.0.0.1:4577/call_log–HVcauses–PRI-----NODEBUG-----19-----CONGESTION-”,“2008-07-26 02:21:19”,“2008-07-26 02:21:24”,5,0,“FAILED”,“DOCUMENTATION”
"",“1007”,“916316891762”,“default”,""“XELA”" <1007>",“SIP/1007-0960de90”,“SIP/VoIP-095ff540”,“Dial”,“sip/16316891762@VoIP|55|o”,“2008-07-26 02:21:03”,“2008-07-26 02:21:13”,“2008-07-26 02:21:26”,23,13,“ANSWERED”,“DOCUMENTATION”
"",“1003”,“916314442965”,“default”,""“mishel”" <1003>",“SIP/1003-09626480”,“SIP/VoIP-09638c90”,“Dial”,“sip/16314442965@VoIP|55|o”,“2008-07-26 02:21:15”,“2008-07-26 02:21:27”,“2008-07-26 02:21:31”,16,4,“ANSWERED”,“DOCUMENTATION”
"",“1006”,“916319729755”,“default”,""“Nellie”" <1006>",“SIP/1006-09626480”,“SIP/VoIP-09635070”,“DeadAGI”,“agi://127.0.0.1:4577/call_log–HVcauses–PRI-----NODEBUG-----19-----CONGESTION-”,“2008-07-26 02:21:36”,“2008-07-26 02:21:42”,6,0,“FAILED”,“DOCUMENTATION”
"",“1007”,“916316891762”,“default”,""“XELA”" <1007>",“SIP/1007-09632450”,“SIP/VoIP-096107b0”,“Dial”,“sip/16316891762@VoIP|55|o”,“2008-07-26 02:21:28”,“2008-07-26 02:21:34”,“2008-07-26 02:21:44”,16,10,“ANSWERED”,“DOCUMENTATION”
"",“1008”,“916317513118”,“default”,""“bj”" <1008>",“SIP/1008-096188e0”,“SIP/VoIP-0962f830”,“DeadAGI”,“agi://127.0.0.1:4577/call_log–HVcauses–PRI-----NODEBUG-----16-----ANSWER-----”,“2008-07-26 02:18:15”,“2008-07-26 02:18:25”,“2008-07-26 02:21:53”,218,208,“ANSWERED”,“DOCUMENTATION”
"",“1006”,“916319729755”,“default”,""“Nellie”" <1006>",“SIP/1006-09632450”,“SIP/VoIP-0960de90”,“DeadAGI”,“agi://127.0.0.1:4577/call_log–HVcauses–PRI-----NODEBUG-----1-----CONGESTION–”,“2008-07-26 02:21:47”,“2008-07-26 02:22:00”,13,0,“FAILED”,“DOCUMENTATION”

thats the time when the call is disconnected…
hope anyone can help me coz our operation are not working well now…