SMS
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Short Message Service (SMS) allows mobile devices to exchange short text messages and was first used in 1992; it works by sending text messages through a Short Message Service Center (SMSC) which delivers the message to the intended recipient's mobile device using cellular network protocols. SMS is widely used for communication, advertising, and value added services but many have switched to messaging apps for lower costs as SMS usage in India has declined significantly since 2013 with the rise of internet-based messaging platforms.
SMS
- 1. Mobile Computing SMS Short Message Service Jainik Patel (112332) Prashant Goswami (112344)
- 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.
- 7. Bits Characters Bits 7 bit 160 char 11208 bit 140 char 16 bit 70 char
- 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
- 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
- 15. Message Flow SM-MT Message Transfer sendRoutingInfo- Delivery ForShortMsg forwardShortMessage sendInfoFor- MT-SMS Message Transfer Deliver Report SM-Delivery ReportStatus Report SMSC GMSC HLR MSC VLR Page Authenticate MS Note: ETSI/GSM MAP sendRoutingInforForShortMsg equivalent in IS41 (North American standard) is SMSrequest mechanism, while forwardShortMessage is Short Message Delivery-Point-to-Point (SMD-PP)
- 16. Message Flow SM-MO Message Transfer Delivery forwardShortMessage sendInfoFor- MO-SMS Message Transfer Delivery Report Delivery Report Report SMSC SMS- IWMSC HLR MSC VLR Access Request Authenticate MS Note: ETSI/GSM MAP forwardShortMessage equivalent in IS41 (North American Standard) is Short Message Delivery-Point-to-Point (SMD-PP) mechanism
- 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)
- 28. Network Infrastructure A generic network infrastructure for realizing the innovative SMS services
- 29. Evolution
- 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.
- 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!
- 39. Question?