Copyright 2010-2015 Obihai Technology, Inc.
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The OBi user can abort the call transfer operation any time before the call transfer completes, but not after. While
entering the target number, the transfer operation is aborted if the user dismisses the Dial Dialog before a complete
number is entered. On the other hand, as soon as a complete transfer target number is entered, the transfer operation
may not be aborted in the blind transfer case (i.e. the type started by user pressing the "Blind Transfer" soft key). In the
attended and semi-attended cases, the phone shows the Complete Call Transfer dialog along with the "Transfer Now"
soft key option as shown in the picture below.
The user may abort the pending transfer operation by dismissing this dialog (with the Home or Cancel Key). In that
case, the pending transfer operation is canceled, but the call to the transfer target continues, albeit reverted to a
regular outgoing call. The user must explicitly end the call to the transfer target if he does not wish to continue with it.
Ending the call to the transfer target at any time before call transfer completes on the other hand cancels the pending
call transfer. The original call with the transferee which may have been placed on hold automatically as a result of
starting a call transfer is not automatically resumed either when call transfer is canceled; the user must explicitly
resume the call to reconnect with the the transferee party. Note also that if the transfer operation eventually fails after
completion (from the OBi user's perspective), the original call with the transferee cannot be restored.
Transfer Signaling
As transferor, if the call with the transferee is on SP
m
and the call with the transfer target on SP
n
where SP
m
and SP
n
point to the same ITSP Profile
X
(including the case
m
=
n
) and
ITSP Profile X – General
::
SignalingProtocol
is SIP and
ITSP Profile X – SIP
::
X_UseRefer
is
true
, the phone will attempt to transfer the call by sending a REFER request to
the transferee with the transfer target’s SIP URL in a Refer-To header. For other cases, the phone will try to bridge the
transferee and transfer target call legs internally.
Limitations of Transfer by Internal Bridging
The phone acts as a proxy of RTP packets sent by each peer of the bridge, without any transcoding. While the phone
will try its best to negotiate the codec to use with each call peer that would be acceptable by the other peer, the
administrator should understand this limitation and configure the codec profiles accordingly. For example, if Google
Voice is to be used, then a call transfer involving a Google Voice call leg must make sure the other call leg supports the
G711U codec.
Conference Calls
A conference call is a conversation involving 2 or more remote parties. In order to start a conference, there must be at
least two calls and with at least one of them in the Connected State and one of them in the Holding State . The
following picture shows such scenario with two calls. To start a conference, highlight one of the calls in the Holding
State and select the
Add to Conf
soft-key option.
