8.2. Services in mobile cellular systems.

In ch. 2 discussed in detail the possible services of the cellular mobile communication system of the GSM standard. Therefore, in this section we will examine the services {services) from the point of view of a mobile communication user. It should be noted that the term services can be interpreted in three basic meanings:

1) services (from the user's point of view);

2) functions (in the technical context);

3) services (in terms of access).

Therefore, very often in the translation literature from English, these concepts are mixed, which complicates the understanding of some simple concepts and processes.

In this section, the term services will be understood as the services provided by mobile network operators to users.

The basic minimum set of services in cellular mobile communication systems includes:

- ordinary telephone connection;

- transmission and reception of facsimile messages;

- transmission and reception of short messages (SMS) and computer data.

Regarding the usual telephone communication, it should be noted that the quality of voice information transmission is not only the cellular network is not inferior to the first one, but is even higher in the GSM standard and at the same time provides unlimited possibility of movement during a call within the coverage area of ​​the mobile communication network.

To transmit and receive fax messages and computer data, in addition to a mobile phone, the use of a mobile fax machine or a laptop computer with the appropriate interface units is required.

The service of sending and receiving short messages (SMS - Short Message Service) consists of the following: a short message (usually up to 160 ... 250 characters) can be received during a conversation, in the standby mode and even when the phone is turned off. In the latter case, the message is recorded in the memory of the computing facilities of the MSC switching center, and the subscriber is notified of the receipt of the message immediately after turning on the mobile phone. The message can be read immediately after receipt or later, the read message can be erased or stored in the memory of the mobile phone for re-reading. The message displayed on the display, if it does not fit entirely, then displayed in parts. If you need to send a short message, the text is typed using the keys of the mobile phone and displayed on the display. Records of the message are either sent to the telephone number specified by the sender, or are not sent, but are stored in memory for sending at another time. Thus, the combination of a cellular mobile phone with a pager is actually ensured, and the subscriber directly controls his message, and delivery to the addressee is guaranteed by the company-operator.

Consider the additional services provided in the systems of cellular mobile communication standard GSM.

1. The call forwarding service (call forwarding, call divert) allows the subscriber to send a call to his phone number to another number which is determined in advance by the subscriber himself. Call forwarding can be unconditional when all incoming calls are forwarded, either conditional if the subscriber number is busy or the subscriber does not answer (does not pick up the phone) for a certain period of time, or if the subscriber is unavailable (his MS is off or out of coverage) . The service in question, like most of the other services, is implemented in the central switch. An incoming call can be redirected to any phone number, for example, to a home landline phone or to a voice mail “inbox”.

2. The call hold service allows the subscriber to interrupt the current call without breaking the communication line. During a pause, the subscriber can accept a new incoming (incoming) call or call another subscriber (outgoing call) and then return to the interrupted call.

3. The call waiting service allows the subscriber to receive a signal about another incoming call during a telephone conversation. In this case, the subscriber is provided with three options for action: refuse the second call; finish the first conversation and go to the second; to interrupt the first conversation, using the call hold service, answer the second call, and upon its termination return to the interrupted first conversation. In the first case, the caller receives a “busy” signal in response, and in the second and third, his call waits until he receives a connection.

4. The conference call service allows you to talk on the phone simultaneously to several (from three or more) subscribers. At the same time, the organizer of the conference call, that is, the subscriber who “gathered” a group of interlocutors, has the ability to temporarily or permanently disconnect from the general conversation of any of the participants, or to end the conference call as a whole.

5. The service barring (or restriction) of certain categories of calls (call barring) allows the subscriber to exclude, for example, all incoming calls or all outgoing calls, or all outgoing international calls. At the same time, to set or remove a ban, an individual password of the subscriber is used, excluding the possibility of unauthorized control of the ban by unauthorized persons.

6. The closed user group service allows you to organize corporate communication between members of a certain group of subscribers, and members of a closed group can communicate with each other without restrictions, and the ability to communicate with the “outside world” via incoming and / or outgoing communication is provided only to individual group members.

7. The service of automatically determining the calling number, as well as the prohibition of determining the number; the ban is imposed by the caller and has a higher priority than the identification number. The possibility of automatically determining the number in combination with the possibility of storing the number in the memory of the subscriber unit allows the subscriber to find out after a while which numbers he received the call from, including which of them went unanswered.

8. The voice mail service allows you to leave a voice message on the subscriber’s personal answering machine if the subscriber cannot receive it at the moment of transmission, for example, if the subscriber unit is turned off or out of network coverage, or if the subscriber does not answer. The addressee receives a notification of the incoming message and listens to it at a convenient time. The subscriber can delete or save the received message to be able to listen to it again. The subscriber is given the opportunity to record an individual greeting, which sounds when the caller is connected to a personal answering machine.

9. Operational information on the cost of services rendered or provided (“advice on payment”).

10. Provision of an open network / user communication line to implement the functions defined by the operator, etc.

The roaming service is very important and convenient, allowing you to use cellular communication not only in “your” network, but also in other networks that are technically compatible with “home” in the presence of appropriate roaming agreements. Not all of the listed services can be implemented in any particular network — it depends on the standard and version of the hardware and software complex used, as well as in some networks there may be services that are not in the above list.