AASTRA 6700i series, 9143, 9480i, 9480i CT SIP Administrator Guide EN - Manual (Page 634)

41-001343-01 Rev 03, Release 3.2.2 6-7
SIP Message Sequence for Blind Transfer
The SIP message sequence for Blind Transfer avoids the transfer target having two simultaneous
calls. Prior to release 1.4, a CANCEL message was sent to the transfer target (if it was in a ringing
state) after sending a REFER to the transferee to complete the transfer. In the 1.4 and later
releases, the CANCEL is now sent before the REFER message.
The following parameter allows the system administrator to force the phone to use the Blind
Transfer method available in software versions prior to 1.4:
sip cancel after blind transfer
This parameter is configurable via the configuration files only.
Configuring SIP Message Sequence for Blind Transfer
SIP Message Sequence for Semi-Attended Transfer
The SIP message sequence for a Semi-Attended Transfer allows the transferor to start the transfer
while the target phone is still ringing.
The following parameter supports different behaviors of a semi-attended transfer:
sip refer-to with replaces
This parameter is configurable via the configuration files only.
The combination of this new parameter (“sip refer-to with replaces”) and the existing parameter
(“sip cancel after blind transfer”) determines how the semi-attended transfer is completed. The
following table shows how the old and new parameters work together:
Configuration Files
For the specific parameter you can set in the configuration files for enabling/disabling the blind transfer
method, see Appendix A, the section,
“Blind Transfer Setting” on page A-237.
IF THEN
The “sip cancel after blind transfer” parameter is
set to 0 and the “sip refer-to with replaces”
parameter is set to 0 The phone sends CANCEL before
REFER for semi-attended transfer.
The “sip cancel after blind transfer” parameter is
set to 1 and the “sip refer-to with replaces”
parameter is set to 0 The phone sends CANCEL after
REFER for semi-attended transfer.
The “sip cancel after blind transfer” parameter is
set to 0 and the “sip refer-to with replaces”
parameter is set to 1 The phone sends REFER with
Replaces for semi-attended transfer
and NO CANCEL.
The “sip cancel after blind transfer” parameter is
set to 1 and the “sip refer-to with replaces”
parameter is set to 1 The phone sends REFER with
Replaces for semi-attended transfer
and NO CANCEL.