basic sms flow

7/25/2019 Basic SMS Flow

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SMS


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SMS

Short Messaging Service (SMS)Also known as Simple Message Service

IntentionDesigned as a replacement for the Pager

The pager allows text messages to be sent to the deviceTo respond you must get to a phoneStill widely used, in

HospitalsMilitaryPoliceIndustry


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SMS

SMS allowed Two way communications of the text messages Maximum character length of 160 characters

This can change though depending on the operator or the character set used Character sets supported are

ASCII + additional European characters Unicode

First Text Was sent in December 1992, to a Vodafone device

Sent by Neil Papworth, saying Merry Christmas

Standard Defined by ETSI and is known as GSM 03.40


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SMS

GSMAt a defined time interval in GSM all devices will listento a transmission.This is when a Digital Control Channel (DCCH) packet ofinformation is being sent across the network.These DCCH packets are used to transfer essential information into thedevices.

Information like a call is in coming

Paging signals from the Base stations, to work out if a handover isneeded

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 duringa phone conversation.


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SMS

SMS Packet formatAll data is transferred in a single DCCH SPACH

packet

SCA Service CentreAddress

MR Message Reference PID Protocol Identifier

PDU Type Protocol Data UnitType

DA Destination Address DCS Data Coding Scheme

VP Validity Period UDL User Data Length UD User Data


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SMS

SMSWhat a packet looks like

Example SMS transmission packet saying Hello

(www.spallared.com/nokia/smspdu/smspdu.htm#_Toc485435709, 2003)
http://www.spallared.com/nokia/smspdu/smspdu.htmhttp://www.spallared.com/nokia/smspdu/smspdu.htm


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SMS OVERVIEW

MS stands forShortMessageService

SMS was first introduced in 1991 in Europe as a text messaging servicebased on European Telecommunications Standards Institute (ETSI)standards for mobile networks

SMS is currently supported on the major mobile network technologiesincluding:

GSM (GlobalSystem forMobile communications) GPRS (GeneralPacketRadioService) CDMA (CarrierDivisionMultiplexAccess)

SMS supports the sending and receiving of text, images, animation andsound

SMS messages are originated and received byShortMessagingEntities(SME). Examples of SMEs are: mobile phones; servers; personal computers


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BASIC NETWORK ARCHITECTURE

SMS!MSC"SMSI#MSC

$LR

SM% MSSMSC MSC"S!S&

VLR

'(tside the scope

of !SM specifications

)* Short Message %ntity +SM%, - sends or receives short messages

.* ShortMessageService Centre +SC, - storesandfor/ards messages 0et/een the SM% and the MS

1* !ate/ay MSC2or Short Message Service +SMS!MSC, receives messages from the SC3

interrogates the $LR for ro(ting information and for/ard the messages to the MSC or S!S&4 $ome Location Register +$LR, a data0ase (sed for permanent storage and management

of (ser"s(0scri0er profiles5* Inter#or6ing MSC2or Short Message Service +SMSI#MSC, receives messages from the MSC or

S!S& and for/ards them to the SC

7* Mo0ile Service Centre +MSC, - performs s/itching f(nctions for mo0ile stations in a geographical area4 Visitor Location Register +VLR, a data0ase that contains temporary information a0o(t

roaming s(0scri0ers* The MSC and the VLR are al/ays on the same platform*

8* Serving !PRS S(pport &ode +S!S&, - performs pac6et s/itching f(nctions for mo0ile stations in a

geographical area* The S!S& is (sed instead of the MSC /hen SMS info is transferred over !PRS*

7. Mobile Station (MS) a device on the mobile network capable of receiving and sendingshort messages


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SMS PROTOCOL SERVICES AND

FEATURES SMS is a point-to-point store and forward technology with 2 basic services:

ShortMessageMobileTerminated (SM-MT) - to transmit a message from the short

message service centre to the mobile station. SMS-DELIVER PDU (ProtocolDataUnit) ShortMessageMobileOriginated (SM-MO) to transmit a message from mobile station toservice centre SMS-SUBMIT PDU

SMS allows message delivery to handsets either active/in-use or powered off Mobile stations receive transport data protocol units (TPDU) denoted as SMS-Deliver Mobile stations send transport data protocol units (TPDU) denoted as SMS-Submit

Note: the TPDU contains the user data (the short message)

SMS protocol permits request of message delivery confirmation report

SMS messages contain up to 140 octets which is equivalent to: 160 Latin characters (7 Bit Coding) Text Mode

70 Unicode characters (double byte) e.g. Arabic Characters, Chinese Characters SMS messages can also contain up to 140 octets of binary information

SMS messages are transported in the core network using SS7 (SignalingSystem7


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SMS SERVICE ELEMENTSValidity Periodis the service element that indicates the time period for which the SMSCwill guarantee the existence of the short message when attempting to deliver it

Service Centre Time Stampis the service element that indicates the time stamp ofmessage arrival at the SMSC

Protocol Identifieris the service element in to indicate higher layer protocol or indicatesinter-working with certain types of telemetic services (e.g. paging, email)

More Messages to Sendis the service element by which a SMSC informs the MS that thereis one or more messages waiting in the SC to be sent to the MS

Priorityis the service element indicating that delivery of the message will be attemptedregardless of the MS being temporarily absent or having no free memory

Message Waitingis the service element that enables the mobile network to provide the HLR,SGSN and VLR with the information that there is a message waiting in the originating SMSCfor a MS

Alert Service Centreis the service element used by mobile networks to inform an SMSCthat a previously unreachable MS (temporarily absent or no memory) is ready to receivemessages


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THE BENEFITS OF SMS TO THE

SERVICE PROVIDER ARE AS FOLLOWS:

Increased call completion on wireless and wireline networks by leveraging

the notification capabilities of SMS

An alternative to alphanumeric paging services

Enabling wireless data access for corporate users

Provision of value-added services such as e-mail, voice mail, and fax mail

integration,reminder service, stock and currency quotes, and airline

schedules. Provision of key administrative services such as advice of

charge, over-the-air downloading, and service provisioning


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PARAMETERS IN HLR PROFILE

TS21-MT SMS

TS 22 MO SMS


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SM-MT (T21)

MS

SC

GSM Network


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SM-MO (T22)

SC

GSM Network

MS


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VAS NETWORK DIAGRAM

SMSC MMSC

Messaging

platform

MSC

HLR

Contentprovider

Mail Server Billing

Firewall

Firewall

USER

SMTP

MAP

MAP

FTP

MM7SMPP

HTTP


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INTERFACES

Subscriberdatabase

Externalapplicatio

n

illing

s!stem

e"mail s!stems

#MS$MS


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MESSAGE TYPES

The SMS Center acts as a store and forward center for ShortMessages (SM) in a cellular network

SMS %enter

%ellularnetwork

M&

M'

&

'

M'

M&


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SMSC


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SHORT MESSAGE SERVICE CENTRE -

SMSC Short Message service Centre plays a central role in the management of SMS messageorigination and SMS message deliveryThe SMS message will be stored at this location on a

FIFO basis .If the device is turned on, the message will be forwarded to that location

Interestingly, detailed functionality of SMSC is outside the scope of standardization, henceseveral vendor specific products and protocols: EMI (ExternalMachineInterface) CMG, now LogicaCMG UCP (UniversalComputerProtocol) Logica, now LogicaCMG

CIMD (ComputerInterface toMessageDistribution) Nokia OIS (OpenInterfaceSpecification) SEMA Group, now Airwide Solutions Computer Access Service and Protocol Ericsson

SMS Forum is an industry initiative to create a common standard SMPP (ShortMessagePeer-to-Peer) using Internet as the transport network

The ETSI/GSM standard does specify minimum mandatory SMSC requirements: Each SMS-Deliver to a MS must have unique time stamp with one second accuracy Only one outstanding SMS-Deliver (i.e. message for which a report not yet received) If requested by MS or SME, initiate overwriting of previously received short messages


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ADDITIONAL FEATURES AND

ISSUES SMS standard allows concatenation of messages to enable transmission of longer messages (i.e.

messages longer than 140 octets)

Short Messages may be compressed with algorithms described in GSM 03.42 Compression only applies to user-data and excludes user-data-header If compressed message are greater than 140 octets, then the messages can be concatenated

In North America wireless subscribers can address text messages using 5-digit numbers (shortcodes)An example of the use of short codes is for SMS voting One objective of short codes is to reduce or minimize Spam Short codes are being used to price and market services (e.g charge back to application provider)

Service gateway products are available that address multi-network (GSM/CDMA) and multi-protocol(e.g. EMI/OIS) inter-working

Security is an emerging concern similar to that with e-mail, for example: SPAM sending of unsolicited messages and ads via SMS (e.g. to entice users to call numbersthat have a high per minute charge)

Virus - resend of message to all numbers in the phones address book (e.g. via a Trojan Horse) Identity Theft - retrieval of personal information from a SIM (SubscriberInterfaceModule) card


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SMSC GLOBAL FUNCTIONALITIES

Intelligent Retry Schedules

Priority Queuing

Acknowledgement Response

Delivery Notification

Validity Period

Message Expiration

Country Prefixing

Deferred Delivery

Blacklisting/White listing

Message Query

Alert Notifications

Message Concatenation

Anti Spoofing


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SMS POLICY

Send the first message in queue

Send the first message in queue to the same

destination address as the new message

Do not send if messages exist to the samedestination address as the new message.

Use only the retry table

Do not send anything, use only retry table


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DELIVERY MECHANISM

Store and Forward

Transaction Mode

Message Throttling in case of SMPP

Message CancellationMessage Replacement


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SMS CALL FLOWS


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MOBILE ORIGINATED SMS FLOW


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FORWARD MO MESSAGE (SCCP

FIELD)

Protocol Info CALG CALD CALG CALD

!SM SMS invo6e mofor/ard SM MSC !T+P9:, SMSC !T P9: ;);


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MO- FORWARD SM (MAP PART)

Invo6e id>

M' for/ard SM> ID?58

SM RP DA> Destination address>>Service Centre address

SM RP 'A> 'riginator Address >>MSISD& + AParty &(m0er,

The MSISD& received from the VLR or from the S!S& is inserted in

this parameter in the mo0ile originated SM

transfer*


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MOBILE-TERMINATED SHORT

MESSAGE


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APPLICATIONTO- MOBILE

MESSAGING


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SMPP(SHORT MESSAGE PEER TO PEER

PROTOCOL Short Message Peer to Peer (SMPP) protocol is an open message-transfer protocol that enables short message entities

(SMEs) outside the mobile network to interface with an SMSC.

Nonmobile entities that submit messages to, or receive messages from an SMSC are known asExternal Short MessageEntities (ESMEs).

The SMPP protocol defines a set of operations for the exchange of short messages between an ESME and an SMSC thedata that an ESME application must exchange with an SMSC during SMPP operations.

Subscribers to an SMS-capable Cellular Network may receive short messages on a Mobile Station (MS) from one ormore ESMEs. The means whereby these messages arrive at the ESME via an interface other than SMPP is beyond thescope of this document. However, examples such ESME applications include:-

Voicemail alerts originating from a VPS (Voice Processing System), indicating voice

messages at a customers mailbox.

Numeric and alphanumeric paging services

Information services. For example, an application that enables mobile subscribers to query

currency rates or share-price information from a database or the WWW and have it

displayed as a short message on the handsets.

Calls directly dialled or diverted to a message-bureau operator, who forwards the message

to the SMSC, for onward delivery to a subscribers handset.

A fleet management application that enables a central station to use the SMSC to

determine the location of its service vehicles and notify the closest vehicle of a service

request in their area.Telemetry applications. For example, a house-hold meter that transmits a short message to

a utility companys billing system to automatically record customer usage.

WAP Proxy Server. A WAP Proxy Server acts as the WAP gateway for wireless internet

applications. A WAP Proxy Server may select an SMS or USSD bearer for sending WDP

datagrams to and receiving WDP datagrams from a mobile station.


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POSITION IN NETWORK -

MSC

SMSC

BTSBSCGMSC

SS7A or

Ater Abis

Air

SS7

SDCCH


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SUCCESSFUL DELIVERY - GSM

RequestSMS!MSC

Sen Routin! Infor"#tion for SM

to $LR /hich incl(des the MSISD&

HLR MSC

SMSC

$MS MCA


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SRI_SM MESSAGE (SCCP FIELD)

%PC DPC Protocol Info CALG CALD

..) @@@ !SM MAP invo6e send ro(ting info for SM P9: SMSC SU:MIS& !T :MSISD&

@@= @8) !SM MAP invo6e send ro(ting info for SM P9: SMSC SU:MIS& !T :MSISD&

@8) @@= !SM MAP ret(rn res(lt last sendro(ting info for SM P: $LR !T P9: SMSC !T

@@= ..) !SM MAP ret(rn res(lt last sendro(ting info for SM P: $LR !T P9: SMSC !T

%PC DPC CALG CALD CALG CALD

..) @@@ P9: SMSC SU:MIS& !T :MSISD& ;);


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SRI_SM MESSAGE (MAP FILED)

S-,SM,/ -ES0,,$umber,121373435557.'6'S-,SM 'race,1373435557.txt


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FEILDS

Invoke id:

MSISDN:

SM-RP-PRI:

This parameter is used to indicate whether or not delivery of the short message shall be attempted when aservice centre

address is already contained in the Message Waiting Data file.

This parameter refers to the MSISDN stored in a Message Waiting Data File in the HLR. It is used to alertthe Service

Centre when the MS is again attainable.

Service Centre Address:

SMSC center GT

SM-RP-MTI:

This parameter shall be present when the feature SM filtering by the HPLMN is

supported by the SMS-GMSC and when the equivalent parameter is received from the short messageservice relay sublayer

protocol.7.6.8.17 SM-RP-SMEA

This parameter represents the RP-Originating SME-address of the Short Message Entity that hasoriginated the SM.

This parameter is used by the short message service relay sub-layer protocol and is formatted

SM-RP-MTI:

protocol.


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HLR MSC

SMSC

$MS MCA

Confir"#tion

Routin! Infor"#tion for SM

incl(ding the IMSI and !T "MSC address


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MT&'%R(ARD&SH%RT&M)SSAG)


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MT&'%R(ARD&SH%RT&M)SSAG)*SCCP 'I)LD+

%PC DPC CALG CALD CALG CALD

..) @@@ SMSC !T invo6e mofor/ard SM ;);


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SM RP DA,

This parameter can contain either an IMSI or a TMSIThe TMSI can 0e provided if it is received from the $LR* The IMSI is

(sed if the (se of the LMSI is not availa0le*

This parameter is omitted in the mo0ile terminated s(0seB(ent SM transfers*

SM RP %A,Service Centre address received from the originating Service Centre is inserted in

SM RP -I,

The short message transfer protocol data (nit received from the Service Centre is inserted in this parameter* A short

message transfer protocol data (nit may also 0e inserted in this parameter in the

message delivery ac6no/ledgement from the MSC or from the S!S& to the Service Centre*

More Mess#!es To Sen,

The information from the MMS indication received from the Service Centre is inserted in this parameter*

To avoid the need for a mo0ile to 0e paged3 a(thenticated etc* for each message /aiting in the Service Centre3 the SC

may indicate to the SMS!MSC that there are more messages to send

-ser error,

Unidentified s(0scri0er

A0sent S(0scri0erSM


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HLR MSC

SMSC

$MS SMPP

'orw#r SM request

Cont#ins MSC Aress GT

IMSI

-ser D#t# *GSM ./01.+


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HLR MSC

SMSC

$MS MCA

'orw#r SM confir"#tion

Inic#tin! "ess#!e eli2er3


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DELIVERY STATUS MESSAGE

Short message transfer protocol data unit informing the

receiving MS of the status of a mobile originated short

message previously submitted by the MS, i.e. whether

the SC was able to forward the message or not, or

whether the message was stored in the SC for laterdelivery.

TP Data: Short message transaction completed,

Short message received by the SME

E)*Stud!*SMS*r! -eport,SMS,s


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DELIVERY

FAILURE MSC DUE

TO TEMPORARYERROR

GSM


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ALERT-SC-MSISDN- ALERT

The Alert-SC is the service element, which may be provided by some GSM PLMNs, to

inform the SC that an MS

1) to which a delivery attempt has failed because the MS is not reachable or because the

MS memory capacity was exceeded;

2) which is now recognized by the PLMN:

a) to have resumed operation (e.g. to have responded to a paging request); or

b) to have memory newly available (which implies that the mobile is reachable).

is again ready to receive one or more short messages. T

The SC may - on reception of an Alert-SC - initiate the delivery


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The Alert flag in the HLR is set in 2 cases:

41.SC sends an SRI message and the HLR replies with the information that thesubscriber is out of memory or not reachable.

42.The HLR is not aware that the subscriber is not reachable (this can happen if wedont shut down the phone properly and just disconnect the battery), in that case

the HLR will reply with IMSI number and MSC address and when the MSC will

try to deliver the message it will fail. After that the SC will send an Inform

message to the HLR indicating that his record about the MS is incorrect.

Command: hgmwp:msisdn=XXXXXXX


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DELIVERY FAILURE TEMPORARY

ERROR GSM

RequestSMS!MSC



HLR MSC

SMSC

$MS MCA


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ERROR GSM

HLR MSC

SMSC

$MS MCA

Confir"#tion




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ERROR GSM

HLR MSC

SMSC

$MS MCA

'orw#r SM request

Cont#ins MSC GT

IMSI

-ser D#t#


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ERROR GSM

HLR MSC

SMSC

$MS MCA

MSC responds /ith temporary

error e*g* a0sent s(0scri0er

Then message /ill go in retry

Sched(le for delivery at later time


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HLR TEMPORARY FAILURE- GSM

HLR MSC

SMSC

$MS MCA

SMSC sets an 2lag in $LR

#hich contains the !T of the

SMSC

and MSISD&

ALERTFOLLOWEDBYASUCCESSFUL


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ALERT FOLLOWED BY A SUCCESSFUL

DELIVERY GSM

$LR sends an SC alertmessage

to the SMSC to notify

that the MS is no/ availa0le

HLR MSC

SMSC

$MS MCA

ALERTFOLLOWEDBYASUCCESSFUL


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ALERT FOLLOWED BY A SUCCESSFUL

DELIVERY GSM

HLR MSC

SMSC

$MS MCA

SMSC sends any pending messages

In D0


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DELIVERY

FAILURE MSC DUE

TO PERMANENTERROR

GSM


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MSC PERMANENT ERROR GSM

Request

SMS!MSC



HLR MSC

SMSC

$MS MCA


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ERROR GSM

HLR MSC

SMSC

$MS MCA

Confir"#tion




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HLR MSC

SMSC

$MS MCA

'orw#r SM request

Cont#ins MSC GT

IMSI

-ser D#t#


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HLR MSC

SMSC

$MS MCA

'orw#r SM confir"#tion(it5 6er"#nent error like

MT "ess#!e not #llowe SMSC

Doesn8t tr3 to eli2er #!#in

SM is elete fro" Db


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Mail > 95e"0k#s53#6:#ricent0co"

' ll M ;) ;

basic sms flow

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