GSM SERVICES
GSM has much more to offer
than voice telephony. Additional services allow you greater flexibility in
where and when you use your phone. You should contact your local GSM network
operator for information on the specific services available to you.
But there are three basic
types of services offered through GSM which you can ask for:
- Telephony (also referred to as
teleservices) Services
- Data (also referred to as bearer
services) Services.
- Supplementary Services
Teleservices or
Telephony Services:
A Teleservice utilises the
capabilities of a Bearer Service to transport data, defining which capabilities
are required and how they should be set up.
Voice Calls:
·
The most basic Teleservice supported by GSM is telephony.
·
Full-rate speech at 13 Kbps
and emergency calls, where the nearest emergency- service provider is notified
by dialing three digits.
·
A very basic example of emergency service is 911 service available
in USA.
Videotext and Facsmile:
Another group of teleservices includes Videotext access, Teletex
transmission, Facsimile alternate speech and facsimile Group 3, Automatic
facsimile Group 3 etc.
Short Text Messages:
SMS (Short Messaging Service) service is a text messaging which
allow you to send and receive text messages on your GSM Mobile phone. Services
available from many of the world's GSM networks today - in addition to simple
user generated text message services - include news, sport, financial, language
and location based services, as well as many early examples of mobile commerce
such as stocks and share prices, mobile banking facilities and leisure booking
services.
Bearer Services or Data Services
Using your GSM phone to receive and send data is the essential
building block leading to widespread mobile Internet access and mobile data
transfer. GSM currently has a data transfer rate of 9.6k. New developments that
will push up data transfer rates for GSM users are HSCSD (high speed circuit
switched data) and GPRS (general packet radio service) are now available.
Supplementary Services
Supplementary services are provided on top of teleservices or
bearer services, and include features such as caller identification, call
forwarding, call waiting, multi-party conversations, and barring of outgoing
(international) calls, among others. A brief description of supplementary
services is given here:
- Multiparty
Service or conferencing: The
multiparty service allows a mobile subscriber to establish a multiparty
conversation.that is, a simultaneous conversation between three or more
subscribers to setup a conference call. This service is only applicable to
normal telephony.
- Call
Waiting: This service allows a
mobile subscriber to be notified of an incoming call during a
conversation. The subscriber can answer, reject, or ignore the incoming
call. Call waiting is applicable to all GSM telecommunications services
using a circuit-switched connection.
- Call
Hold: This service allows a
subscriber to put an incoming call on hold and then resume this call. The
call hold service is only applicable to normal telephony.
- Call
Forwarding: The Call Forwarding
Supplementary Service is used to divert calls from the original recipient
to another number, and is normally set up by the subscriber himself. It
can be used by the subscriber to divert calls from the Mobile Station when
the subscriber is not available, and so to ensure that calls are not lost.
A typical scenario would be a salesperson turns off his mobile phone
during a meeting with customers, but does not with to lose potential sales
leads while he is unavailable.
- Call
Barring: The concept of barring
certain types of calls might seem to be a supplementary disservice rather
than service. However, there are times when the subscriber is not the
actual user of the Mobile Station, and as a consequence may wish to limit
its functionality, so as to limit the charges incurred. Alternatively, if
the subscriber and user are one and the same, the Call Barring may be
useful to stop calls being routed to international destinations when they
are routed. The reason for this is because it is expected that the roaming
subscriber will pay the charges incurred for international re-routing of
calls. So, GSM devised some flexible services that enable the subscriber
to conditionally bar calls.
- Number Identification: There are following supplementary services
related to number identification:
- Calling
Line Identification Presentation: This
service deals with the presentation of the calling party's telephone
number. The concept is for this number to be presented, at the start of
the phone ringing, so that the called person can determine who is ringing
prior to answering. The person subscribing to the service receives the
telephone number of the calling party.
- Calling
Line Identification Restriction: A
person not wishing their number to be presented to others subscribes to
this service. In the normal course of event, the restriction service
overrides the presentation service.
- Connected
Line Identification Presentation: This
service is provided to give the calling party the telephone number of the
person to whom they are connected. This may seem strange since the person
making the call should know the number they dialled, but there are
situations (such as forwardings) where the number connected is not the
number dialled. The person subscribing to the service is the calling
party.
- Connected
Line Identification Restriction: There
are times when the person called does not wish to have their number
presented and so they would subscribe to this person. Normally, this
overrides the presentation service
.
- Malicious
Call Identification: The
malicious call identification service was provided to combat the spread
of obscene or annoying calls. The victim should subscribe to this
service, and then they could cause known malicious calls to be identified
in the GSM network, using a simple command. This identified number could
then be passed to the appropriate authority for action. The definition
for this service is not stable.
- Advice
of Charge (AoC): This service was designed
to give the subscriber an indication of the cost of the services as they
are used. Furthermore, those Service Providers who wish to offer rental
services to subscribers without their own Subscriber Identity Module (SIM)
can also utilize this service in a slightly different form. AoC for data
calls is provided on the basis of time measurements.
- Closed
User Groups (CUGs): This
service is provided on GSM to enable groups of subscribers to only call
each other. This type of services are being offered with special discount
and is limited only to those members who wish to talk to each other.
- Unstructured
supplementary services data (USSD): This
allows operator-defined individual services.
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