Aastra Telecom 41-001343-02 manual SIP Message Sequence for Blind Transfer

Advanced Operational Features

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

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-205.

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:

IF	THEN
The “sip cancel after blind transfer” parameter is set to 0 and the “sip refer-	The phone sends CANCEL before REFER for semi-attended transfer.
to with replaces” parameter is set to 0
The “sip cancel after blind transfer” parameter is set to 1 and the “sip refer-	The phone sends CANCEL after REFER for semi-attended transfer.
to with replaces” parameter is set to 0
The “sip cancel after blind transfer” parameter is set to 0 and the “sip refer-	The phone sends REFER with Replaces for semi-attended transfer and NO
to with replaces” parameter is set to 1	CANCEL.
The “sip cancel after blind transfer” parameter is set to 1 and the “sip refer-	The phone sends REFER with Replaces for semi-attended transfer and NO
to with replaces” parameter is set to 1	CANCEL.

On the transferor phone, the REFER request will always be sent to the transferee.

Configuring SIP Message Sequence for Semi-Attended Transfer

Configuration Files

For the specific parameter you can set in the configuration files for customizing the semi-attended transfer method, see Appendix A, the section, ““Semi-Attended Transfer Settings”” on page A-205.

41-001343-02 REV04 – 05.2014 6-7