User`s manual

MediaPack
SIP User's Manual 216 Document #: LTRT-65408
8.1.2 Consultation / Alternate
 The Consultation feature is relevant only for the holding party (applicable only to the
MediaPack/FXS gateway).
 After holding a call (by pressing hook-flash), the holding party hears dial tone and can
now initiate a new call, which is called a consultation call.
 While hearing a dial tone or when dialing to the new destination (before dialing is
complete) the user can retrieve the held call by pressing hook-flash.
 The held call can’t be retrieved while Ringback tone is heard.
 After the consultation call is connected, the user can switch between the held and
active call by pressing hook-flash.
8.1.3 Call Transfer
There are two types of call transfers:
 Consultation Transfer (REFER + REPLACES)
 Blind Transfer (REFER)
The common way to perform a consultation transfer is as follows:
In the transfer scenario there are three parties:
Party A = transferring, Party B = transferred, Party C = transferred to.
 A Calls B.
 B answers.
 A presses the hook-flash and puts B on-hold (party B hears a hold tone)
 A dials C.
 After A completed dialing C, he can perform the transfer by onhook the A phone.
 After the transfer is completed B and C parties are engaged in a call.
The transfer can be initiated at any of the following stages of the call between A to C:
 Just after completing dialing C phone number - Transfer from setup.
 While hearing Ringback - Transfer from alert.
 While speaking to C - Transfer from active.
Blind transfer is performed after we have a call between A and B, and party A decides to
transfer the call to C immediately without speaking with C.
The result of the transfer is a call between B and C (just like consultation transfer only
skipping the consultation stage).
Note the following SIP issues:
 Transfer is initiated by sending REFER with REPLACES.
 The gateway can receive and act upon receiving REFER with or without REPLACES.
 The gateway can receive and act upon receiving INVITE with REPLACES, in which
case the old call is replaced by the new one.
 The INVITE with REPLACES can be used to implement Directed Call Pickup.