|SMS can be sent with an APP
|What is an SMS?
|Short message service (SMS) is a
globally accepted wireless service that enables the transmission of
alphanumeric messages between mobile subscribers and external
systems such as electronic mail, paging and voice mail systems.
|What are the benefits of SMS?
|SMS provides a powerful vehicle
for service differentiation. The benefits of SMS to the service
- Increased call completion on wireless and wire-line networks by
leveraging the notification capabilities of SMS.
- An alternative to alphanumeric paging services
- Enabling wireless data access to corporate users
- Provision of value added services as email, voicemail, and fax
mail integration, reminder service, stock and currency quotes, and
- Provision of key administrative services such as advice of charge,
over the air downloading and service provisioning
|What are the Elements of the SMS
The above figure shows the basic network structure of the SMS. It
consists of the following:
- Short Messaging Entity: SME is an entity, which may receive or
send short messages. The SME may be located in the fixed network, a
mobile station, or another service center
- Short Message Service Center: SMSC is responsible for the relaying,
storing and forwarding of a short message between an SME and mobile
- SMS-Gateway MSC: is an MSC capable of receiving a short message
from an SMSC, "interrogating a home location register (HLR) for
routing information, and delivering the short message to the visited
MSC of the recipient mobile station.
- Home Location Register: HLR is a database used for permanent
storage and management of subscriptions and service profiles. Upon
interrogation by the SMSC, the HLR provides the routing information
for the indicated subscriber.
- Mobile Switching Center: The mobile switching center (MSC)
performs the switching functions of the system and controls calls to
and from other telephone and data systems
- Visitor Location Register: (VLR) is a database that contains
temporary information about subscribers. This information is needed
by the MSC in order to service visiting subscribers
|What is the Short Message Service
|See SMS Architecture
|What are the basic MAP operations
necessary to provide end-to-end Short Message Service?
|The following basic MAP operations
are necessary to provide end to end short message service:
- Routing Information Request: The SMSC needs to retrieve routing
information from the HLR, in order to determine the serving MSC for
the addressed mobile station. This process is carried out before
delivering the message.
- Point to Point Short Message Delivery: The mechanism provides a
means for the SMSC to transfer a short message to the MSC, which is
serving the addressed mobile station.
- Short message waiting indication: This operation is activated when
a short message delivery attempt by the SMSC fails due to a
temporary failure. This provides a means for the SMSC to request the
HLR to add an SMSC address to the list of SMSC s to be informed when
the indicated mobile station becomes accessible.
- Service Center Alert: The operation provides a means for the HLR
to inform the SMSC which has previously initiated unsuccessful short
message delivery attempts to a specific mobile station, that the
mobile station is now recognized by the mobile network to be
|What Service Elements, does the SMS
|The SMS comprises several service
elements relevant to the reception and submission of short messages:
- Validity Period: The validity period indicates how long the SMSC
shall guarantee the storage of the short message before delivery to
the intended recipient
- Priority: Priority is the information element provided by an SME
to indicate the priority message
In addition, SMS provides a time stamp reporting the time of
submission of the message and an indication to the handset of
whether or not there are more messages to send (GSM) or the number
of additional messages to send (IS41)
|How is the message status notified to
|The SMSC is notified of the
message status through MAP operations. Go to Basic Map Operations.
|What Potential Applications can be
envisaged, using the SMS?
|Some of the potential applications
of SMS technology, utilizing the Mobile Terminated are:
- Notification Services
- E-mail Interworking
- Paging Interworking
- Information Services
|What are the various steps involved
in a "Successful short message transfer attempt"?
|The following steps are involved
in a Successful short message transfer attempt: the short message is
submitted from the SME to the SMSC. After completing its internal
processing, the SMSC interrogates the HLR and receives the routing
information for the mobile subscriber. The SMSC sends the short
message to the MSC using the Forward Short message operation. The
MSC retrieves the subscriber information from the VLR. This
operation may include an authentication procedure. The MSC transfers
the short message to the MS. The MSC returns to the SMSC the outcome
of the Forward Short message operation. If requested by the SME, the
SMSC returns a status report indicating delivery of the short
|Delayed Messages or Undelivered
|Messages sent to a mobile phone
may be delayed for a number of reasons. The two most common are
absent subscriber and mobile memory capacity exceeded.
|In the case of an absent
subscriber a mobile phone may be switched off or temporarily out of
coverage. If the SMSC tries to deliver a message to a mobile phone
under either of these conditions then the mobile phone is noted as
being absent. The SMSC will retry according to the absent subscriber
retry schedule for a limited number of times just in case the mobile
phone has temporarily gone out of coverage (e.g. into a tunnel). If
the mobile phone becomes available (is switched on, changes cells,
receives or makes a voice call, sends a short message or the mobile
phones periodic location update timer expires) then the SMSC will be
informed and the message waiting in the SMSC will get delivered.
Also any new message arriving in the SMSC while the mobile is absent
will trigger a delivery attempt and restart the retry schedule from
the beginning. It should be noticed that when a mobile phone goes
temporarily unavailable and becomes available again in the same cell
there is no notification to the SMSC that it has become available
unless the phone gets turned off then on, changes cells, receives or
makes a voice call, sends a short message or the mobile phones
periodic location update timer expires. Hence the need for the retry
schedule for absent subscriber.
|Mobile Memory Capacity Exceeded
|In the case of memory capacity
exceeded, the SMSC will continually retry to deliver the message
with gradually lengthening intervals. The retry will continue for
the validity period of the message.
|Other Message Delays
|Other less common errors
encountered (e.g. Unidentified Subscriber) are subject to different
retry schedules according to the error condition. Some messages will
retry a few times and will then be purged because by retaining them
at the head of the queue would result in other messages which could
be delivered expiring before delivery can take place.
|Duplication of messages can occur
if the sending entity fails to receive an acknowledgement that a
message has been successfully received by the SMSC and the message