2.5 Overview of some additional services

In the previous section, we considered only the processes of establishing in-station connections. After studying the main stages of this type of compounds, you can imagine other types of compounds. Some of them will be discussed further, after studying the sections on alarm. Below we give only a brief description of additional services.

Dialing services

Connection without dialing

In certain cases, the connection can be established immediately after the subscriber picks up the handset. To do this, use either a self-entered number or (more often) a number entered by the operator.

This service means that at any time or according to a predetermined schedule, at certain intervals after lifting the tube, a permanent channel is established between the ports of the PBX or between the port of this station and the port of another station. Alternatively, it is possible to establish a semi-permanent connection (i.e., a scheduled connection for a long time).

Abbreviated or named set

This service allows you to call other subscribers by dialing a permanent code, typing letters of a name or calling from the directory.

Call Forwarding Services

In this case, the call is forwarded to another subscriber, or to the operator’s console, or to mechanical voices (standard or recorded by the subscriber). This service is set by either the operator or the subscriber. The following options are available for this service:

Unconditional forwarding. Call transfer in any cases.

Call Forward on busy incoming subscriber.

Call Forward No Answer for a specific period of time.

Restriction of call forwarding service. The subscriber has the right to prohibit forwarding to your number.

Call transfer during connection. Allows the subscriber to establish a connection between the calling and third parties, or between two called subscribers.

Waiting services

The service is set either by the operator or by the subscriber. During a call, the subscriber (incoming for the second call) receives a warning signal and puts the other into standby mode (short-cut or dial 1). At the end of the conversation, he can return to the previous connection. An option is to inquire during a conversation, when one of the two subscribers can establish a connection with the third, putting the previous one in the standby mode.

Continuation of the connection after the release of the previous one (installation in a queue)

This service allows the caller (subscriber B) to hang up. After the release of the called line, a reverse connection is established.

If the service provides for the establishment of a queue, then priority is taken into account and the number of the location in the queue changes.

Multilateral Services

Three way conferencing

In this case, the subscriber can connect a third party to the conversation.

Conference call with unlimited number of subscribers

It provides for holding meetings with one-way communication or dialogue of all or part of the participants, a circular call on the list, adding and deleting participants.

Counter Conferencing

In this case, the called party adds the number of participants (hierarchical conferencing is possible).

Administrative Services

Caller ID

This service allows you to determine the caller's number upon request of the operator or equipment.

A request from a subscriber to receive a malicious call is made by dialing 1 or by pressing a lever switch or a special registration code (the procedure is standardized by the European Telecommunication Union).

During an internal call, the operators receive a printout with indication of the numbers of both parties, the time of day and the date. When set to control, the right to hang up is assigned to the called subscriber.

In the case of external malicious calls, actions and information depend on inter-station signaling.

Prohibition of communication

The administration can establish for an individual subscriber a ban on access to certain directions. The following types of prohibitions are available:

• complete prohibition of outgoing communication;
• communication is by password only;
• transfer of outgoing or incoming communication to the operator;
• prohibition of incoming communication from the redirected numbers.

Intervention

In the networks of the Russian Federation long-distance operator or some other services may interfere with the established connection. For example, during a long-distance connection, the subscriber receives a warning signal, after which the long-distance operator informs him of an incoming call.

If the subscriber agrees to accept the call, he hangs up and the initial connection is disconnected in favor of the new one. Some connections may have protection against connection from the outside. This is determined either by the list of participants or by the type of connection (for example, when transmitting over a data line).

other services

Alarm clock

The subscriber can set the time when his device will be given a "call" signal.

Call Back Verification

The subscriber can check his line and, dialing the access code, hang up. After checking the parameters of the line, he will receive a “call” signal.

Password

The operator can set a password by which the subscriber can use certain services.

Prioritized service

Each subscriber is assigned a priority (for example, from 0 to 3).

Depending on the priority of the subscribers participating in the connection, restrictions on office, local or long-distance communication come into effect.

CENTREX services

Such a service simulates for a given group of subscribers an Institutional PBX with a reduced set within the institution and specific services for the institution:

• call forwarding when no answer or busy subscriber to redirect to the operator;
• Outgoing and incoming long-distance and international calls through the operator in case of restriction of subscribers or cost control;
• Calls with the help of the operator with the ordered or proposed waiting;
• operator control with the help of individual types of load;
• centralized responses for incoming calls;
• call the operator during the connection;
• Subscriber search by the operator;
• Queuing on the channel (local, long-distance communication).

Interception services for:

• outgoing and incoming calls;
• non-existent room;
• faulty line;
• access restriction for incoming calls;
• outbound access restriction.

Also currently actively developing services related to data transmission.

ISDN subscriber services were discussed in section 1 (Subscriber Lines and Terminals), and Intelligent Network services will be discussed further.