2. • Short Message Service (SMS) is a text messaging service
component of phone, web, or mobile communication systems.
It uses standardized Communications protocols to allow fixed
line or mobile phone devices to exchange short text messages.
• Also known as Simple Message Service
Short Message Service Defination
3. Why SMS?
• Oldest most reliable means to communicate with mobile users
• Cell phone agnostic
• Everybody is doing it
• Great way to receive emergency messages at the bar
• Was sent in December 1992, to a Vodafone device
• Sent by Neil Papworth, saying “Merry Christmas”
First Text
4. SMS is currently supported on the major mobile network technologies
including:
GSM (Global System for Mobile communications)
GPRS (General Packet Radio Service)
CDMA (Carrier Division Multiplex Access)
Two types of SMS:
SMMT (Short Message Mobile Terminated Point-to-Point)
SMMO (Short Message Mobile Originated Point-to-Point)
SMMT is an incoming short message from the network and is
terminated in the MS (phone or Mobile Station)
SMMO is an outgoing message originated in the MS, and forwarded
to the network for delivery
5. • Messages in Short Message Service (SMS) must be
no longer than 160 alpha-numeric characters and
contain no images or graphics.
• Once a message is sent, it is received by a Short
Message Service Center (SMSC), which must then
get it to the appropriate mobile device.
• To do this, the SMSC sends a SMS Request to the
home location register (HLR) to find the roaming
customer. Once the HLR receives the request, it will
respond to the SMSC with the subscriber's status: 1)
inactive or active 2) where subscriber is roaming.
How it works?
6. • If the response is "inactive", then the SMSC will hold onto the
message for a period of time. When the subscriber accesses his
device, the HLR sends a SMS Notification to the SMSC, and the
SMSC will attempt delivery.
• The SMSC transfers the message in a Short Message Delivery
Point to Point format to the serving system. The system pages the
device, and if it responds, the message gets delivered.
• The SMSC receives verification that the message was received by
the end user, then categorizes the message as "sent" and will not
attempt to send again.
8. By 2013, the country would have more than 750 million mobile
connections; therefore the SMS usage per user would essentially drop.
In a recent survey by Nielson, India, it was revealed that mobile chat
applications such as Nimbuzz and WhatsApp have literally destroyed the
SMS culture and usage inside India. Powered by internet, these
applications are prompting Indians to ditch SMS which normally costs
Re 1 to Rs 1.5 for local numbers and as high as Rs 5 for international
numbers.
SMS vs Chat Apps
9.
10.
11. GSM Short Message Service
• Can contain up to 140 octets, or 160 char.
• To allow messages longer than 160 char.
o SMS concatenation
o SMS compression
• SDCCH signaling channel
• Character sets supported are
oASCII + additional European characters
oUnicode
• Two type of GSM SMS
– Cell broadcast service
– Point-to-point service
12. • Digital Control Channel (DCCH) packet of information is being sent
across the network.
• These DCCH packets are used to transfer essential information into
the devices.
• Information like a call is in coming
• Paging signals from the Base stations, to work out if a handover is
needed
• One of these packet formats is called SMS point to point messaging,
Paging, access control channel (SPACH)
• This message type can be used to carry a text message.
• Advantage of this method is a text message can still be delivered
during a phone conversation.
SDCCH/SPACH
13. SM-MT Service - SMS-DELIVER TPDU Structure
1-10 Octets 1 Octet 2-12 Octets 1 Octet 1 Octets 7 Octets 1 Octet 0-140 Octets
SCA
PDU-
Type OA PID DCS SCTS UDL UD
PDU Type:
Bits7 6 5 4 3 2 1 0
RP UDHI SRI MMS MTI
MTI bit 1 = 0
bit 0 = 0
Parameter Description
SCA Service Centre Address - Telephone number of the Service Centre
PDU Type Protocol Data Unit Type
RP Reply Path - Parameter indicating that Reply Path exists
UDHI User Data Header Indicator - Parameter indicating that UD field contains a header
SRI Status Report Indication - Parameter indicating if the SME has requested a status report
MMS More Messages to Send - Parameter indicating whether or not there are more messages to send
MTI Message Type Indicator - Parameter describing the message type 00 means SMS-Deliver
OA Originator Address - Address of the originating SME
PID Protocol Identifier - Parameter indicating the SMSC how to process the Short Message (e.g. Fax)
DCS Data Coding Scheme - Parameter identifying the coding scheme within the User Data (UD)
SCTS Service Centre Time Stamp - Parameter identifying the time when the SMSC received the message
UDL User Data Length - Parameter indicating the length of the UD-field
UD User Data - Data Field of the Short Message
14. SM-MO Service - SMS-SUBMIT TPDU Structure
Bits
PDU Type:
MTI bit 1 = 0
bit 0 = 1
Parameter Description
SCA Service Centre Address - Telephone number of the Service Centre
PDU Type Protocol Data Unit Type
RP Reply Path - Parameter indicating that Reply Path exists
UDHI User Data Header Indicator - Parameter indicating that UD field contains a header
SRR Status Report Request - Parameter indicating if the MS has requested a status report
VPF Validity Period Format - Parameter indicating whether or not the VP field is present
RD Reject Duplicates – parameter indicating if SMSC will accept a message with same MR and DA from the same OA
MTI Message Type Indicator - Parameter describing the message type 01 means SMS-Submit
MR Message Reference - Successive numbers (0…255) of all SMS-SUBMIT frames sent by the MS.
DA Destination Address - Address of the destination SME
PID Protocol Identifier - Parameter indicating the SMSC how to process the Short Message (e.g. Fax)
DCS Data Coding Scheme - Parameter identifying the coding scheme within the User Data (UD)
SCTS Service Centre Time Stamp - Parameter identifying the time when the SMSC received the message
UDL User Data Length - Parameter indicating the length of the UD-field
UD User Data - Data Field of the Short Message
6 5 1 0
VPF
1-10 Octets 1 Octet 1 Octet 2-12 Octets 1 Octet 1 Octets 0, 1 or 7 Octets 1 Octet 0-140 Octets
SCA
PDU-
Type MR DA PID DCS VP UDL UD
7 4 3 2
RP UDHI SRR RD MTI
17. SMS Architecture GSM Network
IWMSC
Originating MS
SM-SC
Short Message
Sender
GSM Network
SMS
GMSC
MSC
MS
SIM
Terminating MS
BSS
SMS GMSC : SMS Gateway MSC
IWMSC : Interworking MSC
SM-SC : Short Message Service Center
MSC : Mobile Switching Center
BSS : Base Station System
SIM : Subscriber Identity Module
MS : Mobile Station
Figure short message service
network architecture
18. External Short Messaging Entities
An ESME is a device that may receive or send short messages. The short
message entity (SME) may be located in the fixed network, a mobile
device, or another service center.
•VMS:-The VMS is responsible for receiving, storing, and playing voice
messages intended for a subscriber that was busy or not available to take a
voice call. It is also responsible for sending voice-mail notifications for
those subscribers to the SMSC.
20. External Short Messaging Entities (cont.)
• Web:-The growth of the Internet has also affected the world of SMS.
Therefore, it is almost mandatory to support interconnections to the
World Wide Web for the submission of messages and notifications. The
increasing number of Internet users has a positive impact on the SMS
traffic increment experienced in the last few years.
• E-Mail—Probably the most demanded application of SMS is the ability
to deliver e-mail notifications and to support two-way e-mail, using an
SMS–compliant terminal. The SMSC must support interconnection to
e-mail servers acting as message input/output mechanisms.
• Others—There are several other mechanisms to submit short messages
to the SMSC that include, but are not limited to, paging networks,
specialized software for PC–based messaging and operator bureaus.
21. STP and HLR
Signal Transfer Point:-The STP is a network element normally available on
IN deployments that allows IS–41 interconnections over signaling system 7
(SS7) links with multiple network elements.
HLR:- The 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. Also, if the destination station was not available when the
message delivery was attempted, the HLR informs the SMSC that the
station is now recognized by the mobile network to be accessible, and thus
the message can be delivered.
22. VLR and MSC
Visitor Location Register:-The visitor location register is a database that
contains temporary information about subscribers homed in one HLR
who are roaming into another HLR. This information is needed by the
MSC to service visiting subscribers.
MSC:-The MSC performs the switching functions of the system and
controls calls to and from other telephone and data systems. The MSC
will deliver the short message to the specific mobile subscriber through
the proper base station.
23. Air Interface and The Base Station System
Air Interface:-The air interface is defined in each one of the different
wireless technologies (GSM, TDMA, and CDMA). These standards specify
how the voice or data signals are transferred from the MSC to the handset
and back, as well as the utilization of transmission frequencies, considering
the available bandwidth and the system’s capacity constraints.
The Base Station System:-All functions related to the transmission of
electromagnetic radio signals between the MSC and the mobile devices are
performed in the base station (BS). The BS consists of base station
controllers (BSCs) and the base transceiver stations (BTSs), also known as
cell sites or simply “cells.” The BSC may control one or more BTSs and is
in charge of the proper resource assignment when a subscriber moves from
one sector of one BTS to another, regardless of whether the next sector lies
within the same BTS or in a different one.
24. The Mobile Device
The mobile device is the wireless terminal capable of receiving and
originating short messages. Commonly, these devices have been digital
cellular phones, The wireless network signaling infrastructure is based on
SS7. SMS makes use of the mobile application part (MAP), which defines
the methods and mechanisms of communication in wireless networks
and employs the services of the SS7 transactional capabilities application
part (TCAP). An SMS service layer makes use of the MAP signaling
capabilities and enables the transfer of short messages between the peer
entities.
25. Signaling Elements
The MAP layer defines the operations necessary to support SMS. The
following basic MAP operations are necessary to provide the end-to-end
SMS:
– Routing Information Request
– Point-to-Point Short Message Delivery
– Short Message Waiting Indication
– Service Center Alert
26. Service Elements
SMS is comprised of several service elements relevant to the
reception and submission of short messages:
– Message Expiration
– Priority
– Message Escalation
In addition, SMS provides a time stamp reporting the time of
submission of the message to the SMSC 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 (IS–41).
27. • This is a combination of hardware and software
• The SMS message will be stored at this location on a FIFO basis
• If the messages destination is within the local network
• The HLR, is queried to find the current location of the intended
device
• The HLR will also inform if the device is currently turned on
• If the device is off then the HLR is informed that there is a message
waiting
• When the device turns on the HLR informs the SMSC
• The message will then be forwarded to the device
• If the device is turned on, the message will be forwarded to that
location
Short Message Service Centre (SMSC)
30. SMS Protocol Hierarchy
Short Message
Relay Entity
(SMR)
Short Message
Control Entity
(SMC)
Short Message
Relay Entity
(SMR)
Short Message
Control Entity
(SMC)
Short Message
Application Layer
(SM-AL)
Short Message
Transfer Layer
(SM-TL)
Short Message
Relay Layer
(SM-RL)
Connection
Management
Sublayer (CM-sub)
Short Message
Relay Protocol
(SM-RP)
Short Message
Control Protocol
(SM-CP)
Short Message Transfer Protocol (SM-TP)
MSC IWMSC
MS SM-SC
Lower layers
Figure SMS MS-MSC protocol hierarchy (mobile origination)
31. SMS Protocol Hierarchy
Short Message Transfer Layer
• Provides services to transfer SM-AL short msg.
• Generate a reference number SMI (short message identifier)
– SM-AL SMI is not carried between the MS and SM-SC
• Four types of transfer protocol data units (TPDUs)
– SMS-SUBMIT
– SMS-DELIVER
– SMS-STATUS-REPORT
– SMS-COMMAND
32. SMS Protocol Hierarchy
Short Message Relay Layer
• Provides services to transfer TPDUs and delivery reports for SM-TL
• Generate SM-RL SMI for every short message
– SM-RL SMI is mapped to and from SM-TL SMI
– SM-RL SMI at the MS is not carried at the peer entity in the SM-SC
• SM-RP consists of the following RPDU types:
– RP-DATA
– RP-SM-MEMORY-AVAILABLE
– RP-ACK
– RP-ERROR
33. SMS Protocol Hierarchy
Connection Management Sublayer
• Provides services to support the SM-RL
• MS has two SMC entities
– MS-originated (MO) short message service
– MS-terminated (MT) short message service
• SM-CP consists of following protocol elements
– CP-DATA
– CP-ACK
– CP-ERROR
Continue…
34. • MNSMS-ESTablish
– To establish an MM-connection and transfer RPDU on that
establish
• MNSMS-DATA
– Transfer an RPDU on MM-connection
• MNSMS-RELease
• MNSMS-ABORT
• MNSMS-ERROR
SMS Protocol Hierarchy(Cont)
35. SMS VAS Users – City wise Distribution:-
SMS is a popular medium for delivering Value Added Services (VAS); it’s a
valuable revenue source for service providers, almost 5% of service
provider revenue comes from SMS VAS services the highest revenue
earning VAS.
36.
37.
38. SMS advertising is pervasive
• 74% of mobile subscribers in India receive SMS advertising
• 66% of all messages sent in India are premium: content,
advertising, or votes for reality TV, etc
What is your view on this?
Do you actively use SMS today as you used earlier?
Will you miss SMS if telecom companies decide to shut down this
service?
Share your views here!
