Here is the monitor trace. Hopefully I got enough before the reboot to tell what is causing it...
2301817mS CMLineRx: v=20
CMAlerting
Line: type=IPLine 20 Call: lid=0 id=1778 in=0
IE CMIESupplementaryService (3)
Network Facility Extension
sourceEntity: 0
destinationEntity: 0
Interpretation APDU
discardAnyUnrecognisedInvokePdu
AlertingName.Invoke.CodePageISO8859-1
invokeId 26012
user 'Beach Y Main' presentation Allowed
IE CMIERespondingPartyName (228) Beach Y Main
IE CMIERespondingPartyNumber (230)(P:100 S:100 T:100 N:100 R:4) number=3200
IE CMIEFastStartInfoData (6)
2301817mS CMCallEvt: 0.1778.0 218 H323TrunkEP: StateChange: END=B CMCSOverlapRecv->CMCSRinging
2301818mS CMCallEvt: 0.1776.0 218 Operator.1: StateChange: END=A CMCSDialling->CMCSRingBack
2301818mS CMExtnEvt: v=1 State, new=Alerting old=Dialling,0,0,Operator
2301820mS CMExtnTx: v=1100, p1=0
CMAlerting
Line: type=DigitalExtn 2 Call: lid=0 id=1776 in=0
IE CMIESupplementaryService (3)
Network Facility Extension
sourceEntity: 0
destinationEntity: 0
Interpretation APDU
discardAnyUnrecognisedInvokePdu
AlertingName.Invoke.CodePageISO8859-1
invokeId 26012
user 'Beach Y Main' presentation Allowed
IE CMIERespondingPartyName (228) Beach Y Main
IE CMIERespondingPartyNumber (230)(P:100 S:100 T:100 N:100 R:4) number=3200
IE CMIEFastStartInfoData (6)
Timed: 30/09/10 10:28
2301821mS CD: CALL: 0.1776.0 BState=Ringing Cut=3 Music=0.0 Aend="Operator(1100)" (20.1) Bend="Line 20" [Line 20] (270.1) CalledNum=3200 (Beach Y Main) CallingNum=8508196330 () Internal=0 Time=1510 AState=Ringing
2301823mS CMMap: PCG::MapBChan pcp[113]b1r0 cp_b f57f3488 other_cp_b 0 type CGTypeSimple
2301823mS CMMap: a=20.1 b=0.0 PCGS CPReserveCodec (pcp[243]b0r1) true
2301823mS CMMap: PCG::MapBChan pcp[243]b0r1 cp_b f5be73b8 other_cp_b f57f3488 type CGTypeSimple
2301823mS CMMap: a=20.1 b=4.4 M1
2302216mS RES: Thu 30/9/2010 10:28:17 FreeMem=73681924(1) CMMsg=7 (9) Buff=200 908 999 7411 5 Links=9883
2302216mS RES2: RTEngine=0, CMRTEngine=0, Timer=55, Poll=0, Ready=0, CMReady=0, CMQueue=0, VPNNQueue=0
2302597mS CMExtnRx: v=1100, p1=0
CMTransferComplete
Line: type=DigitalExtn 2 Call: lid=0 id=1776 in=0
2302598mS CMTARGET: CMTransferReturnDetails::CMTransferReturnDetails( tt = 40000, extn = 1100 ) called.
2302598mS CMTARGET: TransferProposal: X_call: ID=218 Aend=1100 -> 3200
2302598mS CMTARGET: TransferProposal: Y_call: ID=215 Aend=8508196330 -> 1100
2302598mS CMTARGET: Surviving Call=218
2302598mS CMTARGET: Goodbying Call=215
2302598mS CMTARGET: AEND 8508196330 -> 3200 BEND
2302601mS PRN: CDR - TCPSend maxqueuesize=500 operational=1
2302601mS PRN: CDR - TCPSend maxqueuesize=500 operational=1
2302602mS CMCallEvt: 0.1776.0 218 Operator.1: CompleteTransfer to 0.1769.0 (0.1769.0 215 Operator.0) (Return @ 40000ms -> 1100)
2302602mS CMExtnEvt: Operator: CALL LOST (CMCauseTransfer)
2302602mS CMExtnEvt: Operator: Extn(1100) Calling Party Number(8508196330) Type(CMNTypeUnknown)
2302602mS CMCallEvt: 0.1776.0 -1 Operator.1: StateChange: END=X CMCSRingBack->CMCSCompleted
2302603mS CMExtnEvt: v=1 State, new=PortRecoverDelay old=Alerting,0,0,Operator
2302603mS CMExtnTx: v=1100, p1=0
CMReleaseComp
Line: type=DigitalExtn 2 Call: lid=0 id=1776 in=0
Called[3200] Type=Default (100) Reason=CMDRdirect Calling[8508196330] Type=Unknown Plan=ISDN Pres=Allowed (0)
Cause=126, Transfer(IPO)
Timed: 30/09/10 10:28
2302604mS CMExtnEvt: Operator: CMExtnHandler::SetCurrent( id: 1776->0 )
2302604mS CMCallEvt: 0.1776.0 -1 Operator.-1: StateChange: END=X CMCSCompleted->CMCSDelete
2302605mS CMTARGET: 0.1776.0 -1 Operator.-1: ChangeOriginator: To 5.15.1 218 Q931 Trunk:5 CHAN=1
2302605mS PRN: Alarm log cyclic wrap
2302605mS PRN: Begin Stack Trace
2302605mS PRN: pc=f02ac808
2302605mS PRN: lr=f02ac808
2302605mS PRN: findfunc f02ac7b4 f023a7b0 f02e90e0 f056b57c f05636f0 f0563fc4 f0564298 f0469f34 f046c254 f046c2f4
2302605mS PRN: findfunc f0565ea4 f046c344 f01c35e4 f0239878 f01be5a4 f01be568 00000000 00000000 00000000 00000000
2302605mS PRN: End Stack Trace
2302605mS PRN: ScheduleHistory NOT enabled: Task = CM File = ../platform/platform.cpp Line = 894
2302605mS PRN: .FATAL TLB Data address=00000157 d=5 pc=f02ac808 f02ac7b4 f023a7b0 f02e90e0 f056b57c f05636f0 IP 500 4.2(23)
********** contact lost with 192.168.100.20 at 10:28:28 30/9/2010 - reselect = 1 **********
******************************************************************
********** SysMonitor v6.2 (23) **********
********** contact made with 192.168.100.20 at 10:29:07 30/9/2010 **********
********** System (192.168.100.20) has been up and running for 29secs(29104mS) **********
********** Warning: TEXT File Logging selected **********
********** Warning: TEXT Logging to File STOPPED on 30/9/2010 10:29:07 **********
29104mS PRN: Monitor Started IP=192.168.100.22 IP 500 4.2(23) BB Downtown
(IP Office: Supports Unicode, System Locale is enu)