SHORT MESSAGE SERVICE(SMS)

1. SHORT MESSAGE SERVICE(SMS)

2. MOBILE COMPUTING OVER SMS • GSM supports data access over CSD(Circuit Switched Data). • GSM – digitized not packetized. • CSD – circuit is established & user is charged based on time – the circuit is active & not on the no. Of pkts. Transacted. • GPRS – also known as 2.5G, - next phase within the evolution of GSM, supports data over packets. • WAP – data service supported by GPRS & GSM to access Internet & remote data services. • GSM also include Group 3 facsimile – appropriate fax adapter. • Unique data service of GSM – SMS – enables sending and receiving text messages to & from, GSM mobile phones.

3. SMS • On December 3, 1992, a scientist named Neil Papworth at Sema, a British technology company, sent the first text message “Merry Christmas” to the GSM Operator Vodafone. • Today SMS – most popular data bearer/service within GSM with an average of 1 billion SMS messages(end of 2002) transacted everyday around the world. • Each short message is upto 160 characters in length, when 7-bit Eng. Characters are used.

4. STRENGTHS OF SMS • UNIQUE CHARACTERISTICS OF SMS : • 1) Omnibus nature of SMS : uses SS7 signaling channel, - available throughout the world. • Only bearer – allows a subscriber to send a long distance SMS without – long distance subscription. • Eg., can’t make a voice call to a mobile phone in UK – unless have international calling facility. • But send a SMS to a subscriber in – not having international call facility. • 2) Stateless : sessionless & stateless - every SMS – unidirectional & independent of any context. • Best bearer for notifications, alerts & paging. • Used for Push & unsolicited response. • 3) Asynchronous: In HTTP – there is a request & response pair – is synchronous. • But SMS – asynchronous – ie., even if recipient is out of service – transmission not be abondoned - used as message queues.

5. 4) Self-configurable & last mile problem resistant : Self-configurable. • In WAP or Web – no trivial task to connect to a service from a foreign n/w without any change in the configuration or preference setting. • SMS – no constraints. Can access SMS bearer without any change in the phone settings.( even SMSC or SC are not available). • 5) Non-repudiable : SMS message carries SC & the source MSISDN as part of the message header. • An appln. Connected to SMS – handcraft an MSISDN address like “999” or “MYBANK” . • But an appln. Not handcraft the SC address. • 6) Always connected : this bearer media is always on. • User can’t SWITCH OFF, BAR or DIVERT any SMS mess. • Eg., when a phone is busy, a voice, data or FAX call is in progress. • SMS delivered to MS without any interruption to the call.

6. SMS ARCHITECTURE • 1) SMS ARCHITECTURE – fig. 6.1 • 2) SMMT(SHORT MESSAGE MOBILE TERMINATED) – fig. 6.2 • 3) SMMO(SHORT MESSAGE MOBILE ORIGINATED) – fig. 6.3 • 4) SMS AS AN INFORMATION BEARER • Very popular bearer – person-to-person, point-to-point, mobile-to-mobile messaging domain. • Gaining popularity in enterprise applns., services provided by independent service providers (ASP) & notification services • Fig . 6.4. • To use SMS – as a bearer- connect the services running on the Enterprise Origin Server to the SC thru’ SME (Short Message Entity) or ESME (External Short Message Entity). • SME – generally an SMS g/w.

7. Operator-centric Pull • For SMMO – SC is mandatory. • Operators offer diff. Inf. On demand & entertainment services. • Done via connecting an Origin Server to SC via an SMS g/w. • These service provider known – MVNO(Mobile Virtual N/w Operators). • Virtual Operators develop diff. Sys, services & applns., • Many enterprises uses MVNOs – to serve to mobile phone users. • Ie.,few banks in India to offer balance enquiry. • Eg., HDFC – customer needs to use these services , thus register for the service. • During registration, the HDFC customer needs to mention the MSISDN of the phone. • Once user registered – he enters “HDFCBAL” & sends a mess. To a service no. Like 333 as an MO mess. • SC – delivers MO to SME connected to this service. • Response is from the enterprise appln. – delivered to MS as an MT mess. From SME.

8. Std. Protocols used for this communication. • 1) SMPP – Short Message Peer to Peer. • 2) CIMD • 3) between SME & Origin Server – SOAP (Simple Object Access Protocol) • HTTP – helps user to get inf. From internet via SMS. • SMS queries are keywords driven like “CRI” for live cricket score , etc.,

9. Operator-independent Push • Similar to MO, an MT mess. – delivered from a n/w in India to an MS of UK roaming in Germany. • Fig. 6.5 • Ie., Push – any alert , notification or even response from a pull mess. Generated by an appln., - serviced by any n/w. & delivered to any GSM phone. • Eg., some credit cardcompanies in India send SMS notifications to its cardholders in diff. n/ws using operator-independent push.

10. VALUE ADDED SERVICES THRU’ SMS • VAS defined as services – share one or more of the foll. Characteristics : • 1) Supplementary service but adds value to total service offering. • 2) Stimulates incremental demand for core services offering. • 3) Stands alone in terms of profitability and revenue generation potential. • 4) Can sometimes stand-alone operationally. • 5) Does not cannibalize basic serive unless clearly favorable. • 6) Can be an add-on to basic service,& as such, may be sold at a premium price. • 7) May provide operational and/or administrative synergy b/w or among other services . • GSM’s goal – to offer the n/w infrastructure. • Voice, SMS – basic services provided by a GSM operator. • Offering diff. Other services using SMS as a bearer – is VAS. • Most popular VAS over SMS – entertainment & inf. On demand.

11. Inf. On demand – has 3 categories • 1) Static Information : not change frequently. Eg., restaurant guide. • Contents fall in mass market category. • 2) Dynamic Inf. : changes in days. Eg., daily horoscope changes on daily basis. Mass market content fall in this category. • 3) Real-time Inf. : changes continually. Third-party contents fall in this category. Eg., scores in a live cricket match. • All enterprise contents fall in this category. • User Interface in SMS Value Added Services : • SMS – sessionless & short transaction model. • For a SMS based service,user interface always – keyword-based. • eg.1, to know the latest news. Enter News & send it to VAS service. • If business news, enter News biz. • News – keyword • Eg.2, RSA 2627 Bangalore New Delhi 20 01. – to find the seat availability on the Indian Railways train No. 2627 from Bangalore to New Delhi on Jan’ 20th. • Response for this – given in book.

12. If response > 160 char. – split the response into multiple mess responses. • Advised to a seq. No. Like .....1/3,......2/3, and ..........3/3 – for 1st,2nd, 3rd mess. • VAS EXAMPLES : • 1) NEWS/STOCK QUOTES SERVICE :get the latest news or stock inf. • Keyword for news – News, for stock inf. (Bombay Stock Inf.) – BSE • For News & Stock - must have relationship with some content provider who will supply the up-to-date inf. • Eg. Tie up with CNN – for international news, The Indian Express – general news, weather.com – weather news. • For stock quote – tie up with Bombay Stock Exchange or National Stock Exchange. • 2) SESSION-BASED CHAT APPLN. • Chat service – session-oriented transaction. • Needs to explicity log out or logged out implicitly. • Every time user sends a chat keyword, need to know the previous trans. • MSISDN no. Phone – used as session key.

13. 3) EMAIL THRU’ SMS • Trans. Oriented dialogue. • User mess. Will be – eg., mail roopa@iitb.ac.in we will meet tomorrow 6:00 p.m. • In above mess. – mail id & body of the mess. Given • 4) HEALTH CARE SERVICES • This needs both pull & push . • A typical appln. – be ICU sys. – include alerts to doctor. • Eg., in status monitoring service – doctor or nurse can enquire the status of a patient in ICU.- short trans. – pull service • Even the doctors & nurses – notified periodically about the status of the patients. - push service. • 5) MICRO-PAYMENT SERVICES • Session-oriented dialogue. • In this appln. – will be some no. Of identifier- pasted on the vending machine. • Customer enter this no. & sends a request to purchase a product. • Service provider – authenticate the user & check whether the user has sufficient money.

14. Based upon the money trans. – approved or rejected. • If approved – authentication mess. – sent back to the vending machine. • Vending machine – ask the user to select the product. • User selects product – shop dispense the product – vending machine send a mess. To VAS indicating shop that the product – dispensed. • ALERT SERVICES • Time-based : • Proactive alerts sent to phones @ pre-assigned time. • Watermark-based: • Whenever stock price goes up or falls down to a certain level, alerts are sent. • Other services – cricket score – periodic alert (every 10 minutes). • LOCATION-BASED SOFTWARE : • Eg., road direction, restaurant guide etc., • Some location-aware VAS services provide shopping alerts. • In locaation-based services – only the inf. Relevant to the current location is provided.

15. Eg., in shopping service – alerts on discount or sale inf. – when they pass thru’ close the shopping mall. • In restaurant guide, if a person in his office & sends Res to VAS – then receives – restaurants in & around his office. • For location-aware s/w – precise location needs to be determined. • Either from the n/w or from the device. • Using n/w – Time Advancing Technique used within the BTS. • Using device – 1) Cell ID-based sys. 2) Global Positioning Sys.(GPS)-based sys. • 1) In a CID-based sys. – CID of the current BTS –determined. • Needs mapping of the cell id to the geographical loc. • Signal strength from all the diff. CIDs - extracted from the device & sent to the server thru’ SMS. • Loc. Of user – determined using signal strength & triangulation algs. • 2) In a GPS-based sys. – loc. Determined thru’ GPS receiver installed within the phone. • Computes position, velocity & time of a GPS reciever. • Exact loc. Provided to offer direction inf.

16. Based on the velocity also direction be identified. • GPS sys. – not dependent on n/w operator. • Fig. 6.6 – shows the architecture of VAS. • ACCESSING THE SMS BEARER • 2 ways of accessing: • 1) use a mobile phone as a GSM modem & connect it to computer. • 2) Use the SMSC of an operator thru’ SMPP or similar interface. • GSM MODEM (OVER THE AIR)