SIP User's Manual
1
.
Overview
Version 2.4
17
June 2008
Call Forward (3xx Redirect Responses); refer to '
581H604H
Call Forward'
on page
582H605H
17
.
Call Waiting (182 Queued Response); refer to '
583H606H
Call Waiting'
on page
584H607H
17
.
The above services are permanently active and cannot be disabled.
For example setups of Supplementary Services, refer to Section '
585H608H
Configuring
Supplementary Services
' on page
586H609H
149
'.
1.4.3.1.1 Call Hold and Retrieve
Call Hold and Retrieve can be initiated by using the corresponding features of the ISDN
Phone.
Hold is performed by sending a REINVITE with the IP address 0.0.0.0 and ‘a=inactive’ in
the SDP.
The ISDN user can retrieve the call using the appropriate features of the ISDN phone.
1.4.3.1.2 Call Transfer
The system supports call transfer by the SIP side. The system supports the following two
types of call transfers:
Consultation Transfer (Refer and Replaces)
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 and Party C = transferred to.
•
A Calls B.
•
B answers.
•
A holds the call and dials a call to C.
•
A connects B to C, and then A disconnects.
•
After the transfer is complete, the B and C parties engage in a call.
Blind Transfer (Refer)
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. It can do so by sending a
REFER message.
The result of the transfer is a call between B and C (similar to consultation transfer,
but skipping the consultation stage).
1.4.3.1.3 Call Forward
The gateway supports call forward using 3xx responses. If the gateway receives a 3xx
response to an invite, the call is forwarded to the new destination.
1.4.3.1.4 Call Waiting
The gateway supports Call Waiting using the SIP Queued message. If a Queued message
is received, the gateway plays the Queued tone to the ISDN phone.
1.4.3.2 Fax and Modem Settings
Fax and modem settings are described in '
587H610H
Configuring Fax and Modem
' on page
588H611H
144
.
