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Global Call IP Technology Guide — November 2007 73
Dialogic Corporation
IP Call Scenarios
3.2.7.4 Party B Timeout
As indicated in Figure 24, the user or application at the transferred-to endpoint (party C) may
receive the transferred call after the T4 timer expires. If this is the case and the callIdentity is
cleared as a result of the T4 expiry, the transferred-to endpoint will clear or reject the transferred
call as indicated by a GCEV_DISCONNECTED event at the transferred endpoint (party B) and a
GCEV_INVOKE_XFER_FAIL event at the transferring endpoint (party A). Both the original
primary call and the secondary, consultation call are left connected and in the
GCST_CONNECTED state from the perspective of both A and B (primary) and A and C
(secondary); GCST_CONNECTED state from the perspective of both A and B.
Figure 24. H.450.2 Supervised Call Transfer Failure - Party B Timeout
A
(Transferring)
IP CCLib
B
(Transferred)
App
B
(Transferred)
IP CCLib
C
(Transferred To)
App
C
(Transferred To)
IP CCLib
A
(Transferring)
App
FACILITY(ctIdentify.Invoke)
GCEV_REQ_
INIT_XFER(CRNs)
gc_AcceptInitXfer(CRNs)
FACILITY(ctIdentify.ReturnResult)
gc_InvokeXfer
(CRNp, CRNs)
FACILITY(ctInitiate.Invoke)
SETUP(ctSetup.Invoke)
GCEV_REQ_XFER
(CRNp)
gc_AcceptXfer(CRNp)
GCEV_
ACCEPT_XFER
(CRNp)
gc_MakeCall(CRNt)
GCEV_DIALING
(CRNt)
Pre condition: Primary call between A and B is connected.
Secondary (consultation) call between A and C is connected (not shown).
KEY:
CRNp - primary call
CRNs - secondary
(consultation) call
CRNt - transferred call
time interval in excess of
timer T4 duration...
20 secs. elapse before
SETUP arrives,
thus timer T4 expires
gc_DropCall(CRNt)
GCEV_
DROPCALL(CRNt)
gc_ReleaseCallEx
(CRNt)
GCEV_
DISCONNECTED
(CRNt)
RLC
Invalid callIdentity, thus
call is cleared internally
FACILITY(ctInitiate.InvokeReturnError)
GCEV_
INVOKE_XFER_
FAIL(CRNp)
Post condition:
Primary call between A and B remains connected.
Secondary (consultation) call between A and C remains connected.
T4 timer started
(20 secs.)
GCEV_ACCEPT_
INIT_XFER_FAIL(CRNs)