T305 and T308 are timers used in the call clearing process. T305 is started when the network node initiates call clearing, and if it expires before a release is received from the mobile station (MS), the network node will send a release to the MS and start T308. If T308 expires without a release complete, the network node will send another release and restart T308. If T308 expires again, the network node will forcibly release all resources. The values of T305 and T308 can be found in parameters and changed using commands.

1. EricssonInternal|2011-01-11|Page2
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T305andT308isthetimerusedinthecallclearingprocess.
Whennetworknodeinitiatethecallclearing,thenormalprocessisas:
NetworkNodeMS
|--------------------------------------|Disconnect,StartingT305inNetworkNode
|--------------------------------------|Release
|---------------------------------------|ReleaseComplete
Inaabnormalcase,ifT305expiredbutReleaseisnotreceivedfromMS,thenNetworkNodewillsendtheReleasetoMS,andstarting
T308.IfT308expiredbutReleasecompleteinnotreceivedfromMS,thenNetworknodewillsendReleaseagaintoMSandrestartT308
again.WhenT308expiredagain,thenNetworkNodewillforcereleaseallMMresource.Thisabnormalprocessisasfollowed:
NetworkNodeMS
|--------------------------------------|Disconnect,StartingT305inNetworkNode
|-------------------------------------|ReleaseT305expiredinNetworkNode,sendReleaseandstartingT308inNetworkNode.
|---------------------------------------|ReleaseT308expiredinNetworkNode,sendReleaseagainandrestartT308inNetworkNode.
T308expiredinNetworkNodeagain,theNetworknodewillforcereleaseallMM
resource.
ThevalueofT305andT308canbefoundinMTACCandMTBCCrespectively.VariableCDT305andCDT308isusedtocontrolthetimer.
CDT305=2*T305+2
CDT308=2*T308+2
$POUJOVF$POUJOVF$POUJOVF$POUJOVFǚǚǚǚ

2. EricssonInternal|2011-01-11|Page3
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1Sec30Sec
Anapplicationparameterdeterminesthetime
supervisionperiodbetweensendingof
RELEASEmessageandreceivingof
RELEASECOMPLETEorRELEASE
messageusingtheT308timer.
Valuerange=1s-255s
MTACC
MTBCC
T308
1Sec30Sec
Anapplicationparameterdeterminesthetime
supervisionperiodbetweensendingof
DISCONNECTorRELEASEmessageusing
theT305timer.
Valuerange=1s-255s
MTACC
MTBCC
T305
3FDPNNFOEF3FDPNNFOEF3FDPNNFOEF3FDPNNFOEF
E7BMVFE7BMVFE7BMVFE7BMVF
%FGBVMU%FGBVMU%FGBVMU%FGBVMU
WBMVFWBMVFWBMVFWBMVF
%FTDSJQUJPO%FTDSJQUJPO%FTDSJQUJPO%FTDSJQUJPO#MPDL#MPDL#MPDL#MPDL5JNFS5JNFS5JNFS5JNFS
Whenthetimerexpiredthefirsttime,themessagereleaseissenttotheMS
AndthetimerT308isstarted,ifthetimerexpiresasecondtime,thecalliscleared

3. EricssonInternal|2011-01-11|Page4
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Fromtheladderdiagram,it
isclearthatif
T305+2*T308
(N200+1)*T200
thenTchdropdueT200
timerexpirywilldecrease
fromOSSstatistic.