AudioCodes Mediant 4000 SBC User Manual page 457

CHAPTER 19 Coders and Profiles
Parameter
'Play RBT To Transferee'
sbc-play-rbt-to-xferee
[IpProfile_
SBCPlayRBTToTransferee]
Description
For example, assume that the device establishes a call
between A and B. If B initiates a call transfer to C, the
device receives an INVITE with the Replaces header from
C. If A supports the Replaces header, the device simply
forwards the INVITE as is to A; a new call is established
between A and C and the call between A and B is
disconnected. However, if A does not support the
Replaces header, the device uses this feature to terminate
the INVITE with Replaces header and handles the transfer
for A. The device does this by connecting A to C, and
disconnecting the call between A and B, by sending a SIP
BYE request to B. Note that if media transcoding is
required, the device sends an INVITE to C on behalf of A
with a new SDP offer.
Enables the device to play a ringback tone to the
transferred party (transferee) during a blind call transfer, for
the SIP entity associated with the IP Profile (which does
not support such a tone generation during call transfer). The
ringback tone indicates to the transferee of the ringing of
the transfer target (to where the transferee is being
transferred).
■ [0] No (Default)
■ [1] Yes
Typically, the transferee hears a ringback tone only if the
transfer target sends it early media. However, if the
transferee is put on-hold before being transferred, no
ringback tone is heard.
When this feature is enabled, the device generates a
ringback tone to the transferee during call transfer in the
following scenarios:
■ Transfer target sends a SIP 180 (Ringing) to the device.
■ For non-blind transfer, if the call is transferred while the
transfer target is ringing and no early media occurs.
■ The 'Remote Early Media RTP Behavior parameter is
set to Delayed (used in the Skype for Business
environment), and transfer target sends a 183 Session
Progress with SDP offer. If early media from the
transfer target has already been detected, the
transferee receives RTP stream from the transfer
target. If it has not been detected, the device generates
a ringback tone to the transferee and stops the tone
generation once RTP has been detected from the
transfer target.
For any of these scenarios, if the transferee is put on-hold
by the transferor, the device retrieves the transferee from
hold, sends a re-INVITE if necessary, and then plays the
ringback tone.
Note: For the device to play the ringback tone, it must be
loaded with a Prerecorded Tones (PRT) file. For more
information, see Prerecorded Tones
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Mediant 4000 SBC | User's Manual
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