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Configuring call services
Call services include call waiting, call hold, call forwarding, call transfer, and call backup.
Call waiting
When subscriber C calls subscriber A who is in a conversation with subscriber B, the call is not rejected.
Like a normal call, subscriber C hears ringback tones, and subscriber A hears call waiting tones. This is
call waiting.
Subscriber A can answer the new call by pressing the flash hook or hanging up to end the call with
subscriber B. In the former case, subscriber B is held. In the latter case, subscriber A is immediately
alerted and can pick up the phone to answer the call originated by subscriber C.
Call hold
When subscriber A in a conversation with subscriber B presses the flash hook, subscriber B is held (in
silent state or listening to waiting tones). The system plays dial tones to subscriber A, waiting for
subscriber A to initiate a new call. If subscriber A fails to dial within a period of time, the system stops
playing dial tones and subscriber A cannot initiate a new call. Subscriber A can resume the call with
subscriber B by pressing the flash hook again. This is call hold
Call forwarding
When the called party cannot answer a call, the called party notifies the calling party of the
forwarded-to number. The calling party re-initiates a call request to the new destination. This is call
forwarding. For example, subscriber A calls subscriber B who is busy, and subscriber A forwards the call
to subscriber C. Then, subscriber A and subscriber C establishes a call. Subscriber A is the initiator of call
forwarding, subscriber B is the recipient, and subscriber C is the final recipient.
The system supports the following types of call forwarding:
• Call forwarding unconditional—Forwards an incoming call to the predetermined destination,
regardless of the state of the called party.
• Call forwarding busy—Forwards an incoming call to the predetermined destination when the
called party is busy.
• Call forwarding no reply—Forwards an incoming call to the predetermined destination when the
called party provides no answer within a configurable period of time.
• Call forwarding unavailable—Forwards an incoming call to the predetermined destination when
the voice interface of the called party is shut down by executing the shutdown command.
Call transfer
Subscriber A (the originator) and subscriber B (the recipient) are in a conversation. Subscriber A presses
the flash hook to place the call on hold. Subscriber A dials another number to originate a call to
