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Chapter 4: Configuring your VOIP
Multi-Tech Systems, Inc. 72
Supplementary Services
Supplementary Services features derive from the H.450 standard, which brings to the VOIP telephony
functionality once only available with PSTN or PBX telephony. Even though the H.450 standard refers only to
H.323, Supplementary Services are still applicable to the SIP and SPP VOIP protocols.
Of the features implemented under Supplementary Services, three are very closely related: Call Transfer, Call
Hold, and Call Waiting. Call Name Identification is similar but not identical to the premium PSTN feature
commonly known as Caller ID.
Call Transfer. Call Transfer allows one party to re-connect the party with whom they have been speaking to a
third party. The first party is disconnected when the third party becomes connected. Feature is used by a
programmable phone keypad sequence (for example, #7).
Call Hold. Call Hold allows one party to maintain an idle (non-talking) connection with another party while
receiving another call (Call Waiting), while initiating another call (Call Transfer), or while performing some other
call management function. Feature is used by a programmable phone keypad sequence (for example, #7).
Call Waiting. Call Waiting notifies an engaged caller of an incoming call and allows them to receive a call from a
third party while the party with whom they have been speaking is put on hold. Feature is used by a
programmable phone keypad sequence (for example, #7).
Call Name Identification. When enabled for a given VOIP unit (the ‘home’ VOIP), this feature gives notice to
remote VOIPs involved in calls. Notification goes to the remote VOIP administrator, not to individual phone
stations. When the home VOIP is the caller, a plain English descriptor will be sent to the remote VOIP identifying
the channel over which the call is being originated (for example, “Calling Party - Omaha Sales Office Line 2”). If
that VOIP channel is dedicated to a certain individual, the descriptor could say that, as well (for example “Calling
Party - Harold Smith in Omaha”). When the home VOIP receives a call from any remote VOIP, the home VOIP
sends a status message back to that caller. This message confirms that the home VOIP’s phone channel is
either busy or ringing or that a connection has been made (for example, “Busy Party - Omaha Sales Office Line
2”). These messages appear in the Statistics – Call Progress screen of the remote VOIP.
Note that Supplementary Services parameters are applied on a channel-by-channel basis. However, once you
have established a set of supplementary parameters for a particular channel, you can apply this entire set of
parameters to another channel by using the Copy Channel button and its dialog box - to copy a set of
Supplementary Services parameters to all channels, select “Copy to All” and click Copy.
Figure 4-24: Supplementary Services
The Supplementary Services fields are described in the tables below.