R2511-HP MSR Router Series Voice Configuration Guide(V5)

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Call transfer
Subscriber A (originator) and subscriber B (recipient) are in a conversation. Subscriber A presses the
flash hook and the call is put on hold. Subscriber A dials another number to originate a call to subscriber
C (final recipient). After Subscriber A hangs up, the call between subscriber B and subscriber C is
established. This is call transfer.
To perfect the call transfer feature, the device supports the call recovery function after the call transfer fails.
In other words, if subscriber C in the previous example is in a conversation with another subscriber and
cannot establish a conversation with subscriber B, the call between subscriber A and subscriber B is
recovered.
Call backup
This call service is used when, after initiating a call to the called party, the calling party is unable to
receive a response, or the VoIP device of the called party denied the call request from the calling party.
In this case, if there is another link (PSTN link or VoIP link) to the called party, the calling party re-initiates
a call to the called party over the new route. This is call backup.
Hunt group
Multiple voice subscriber lines are configured with the same called number to form a hunt group. If the
voice subscriber line with the first priority is unavailable when a call setup request to the called party is
received, the call will still be established through another voice subscriber line in the hunt group.
Call barring
Call barring includes incoming call barring and outgoing call barring.
Incoming call barring usually refers to the Do Not Disturb (DND) service. When incoming call barring is
enabled on a voice subscribe line, calls originated to the attached phone will fail.
When outgoing call barring is enabled on a voice subscriber line, calls originated from the attached
phone will fail, too.
Message waiting indication
The message waiting indication (MWI) feature allows a voice gateway to notify a subscriber of
messages received from a voice mailbox server. For example, when a call destined to subscriber A is
forwarded to the voice mailbox server, the server will notify the state change to the voice gateway. When
subscriber A picks up the phone, subscriber A will hear the message waiting tone without needing to
query the mailbox.
Three-party conference
When subscriber A has a call with subscriber B and holds a call with subscriber C, A can make C join
the current conversation to implement a three-party conference.
During a three-party conference, a passive participant can initiate a new call to create another
conversation. In this way, conference chaining is implemented, and each conference initiator serves as
a conference bridge.