Mobile Computing

Mobile Computing

Tanvir Ahmad [email protected]

Air University, Islamabad

Objectives• This section explores the services that are provided in a

GSM network.• After completing this section you will be able to:

– Relate the services that can be offered to GSM subscribers like • Teleservices • Supplementary Services• IN (Intelligent Services)• CAMEL (Customized Application for Mobile network

Enhanced Logic)

Teleservices

• Telephony• Emergency Call• Short Message Cell Broadcast• Short Message Service• Fax• User's Data Call Features• Voice Messaging

Teleservices

Teleservices• Teleservices cover regular telephony, emergency calls, voice

messaging, and short messages handling.• The most important service provided by GSM users is telephony which

enables bi-directional speech calls to be placed between GSM users and any telephone subscriber who is reachable through the general telephony network.

• Fixed telephone subscribers worldwide as well as mobile network subscribers or subscribers of specific networks connected to a public telephone network can be reached.

• Before either Mobile Originated or Mobile Terminated calls can be established, the mobile telephone must be switched on and registered into the system.

Teleservices

Teleservices• To place an emergency call enter 112 followed by SEND. Additional

means to place such call are also allowed by a dedicated button.• The Mobile Telephone supports the initiation of an emergency call

without a SIM present in it, regardless of the call being accepted or not by the network.

• Note that calls to national emergency services may be standard for the country of the serving GSM network (number 17 to call the police in France, number 911 to make an emergency call in U.S.A.).

• However, with the exception of code "112", these are not treated within the GSM network as "teleservice emergency call" and would require a valid IMSI.

Teleservices

Teleservices• The cell broadcast enables an Information Provider to submit short messages for

broadcasting to a specified area within the GSM network.• The cell broadcast service has the following features:

– The cell broadcast message is sent (on control channels) in a limited area, defined by the originator of the message, by agreement with the GSM Operator.

– The mobile telephone only receive the broadcast message in idle mode.– The short message function running in the mobile is able not to store broadcast messages

which are not wanted or which have already been received.– The mobile telephone does not send acknowledgment.– The GSM network continuously sends cell broadcast messages so that all such messages are

sent in turn, an then repeated. On the other hand, the cycle time is short enough for important messages to be received by travelers (subscribers) moving through a group of cells.

– The maximum length of each cell broadcast message will be 93 characters and GSM specifications allows up to 15 of these 93 character messages treated as segment of a longer message.

Teleservices

Teleservices• Short Message Service (SMS) allows the point to point transmission of

a short message to/from MS, using their IMSI.• A short message is an alphanumeric string that can be up to 160

characters long.• Two different types of short message are defined:

– Short message MT/PP (Mobile Terminated / Point to Point),– Short message MO/PP (Mobile Originated / Point to Point).

• Point to point messages may be sent or received when the MS is engaged on a call (voice or data), or in idle mode. However, messages which overlap the boundary of such a call, or during a handover, may be lost, in which case they will be sent again.

Teleservices• Messages may be input to the SC from a fixed network customer by means of

a suitable telecommunication service either from the fixed network or from a mobile network customer.

• An acknowledgment indicates that the GSM Network has successfully transferred the message to the mobile telephone or the SC.

• Optionally, the SC may offer final delivery notification to the originator. This delivery report indicates whether this particular message has been correctly received at the receiving station or not, to the extent that the SC is able to establish this.

• It does not indicate whether the message has been read. If the delivery report is negative, it includes the failure cause. The delivery report is sent to the originator, if reachable, as soon as the information is available.

Teleservices

Teleservices

• Fax transmissions are possible via a PLMN only with a Fax-group3 (14.4 kbps).

• Two modes are available:– Manual mode allows to switch alternatively from voice

transmission to fax transmission,– Automatic mode allows to send and receive a fax without any

human intervention;

• However, voice transmission is impossible in this mode.

Teleservices

Teleservices

• Connections can be made with a suitable data/fax kit adaptation either to other Mobile Station or to other data users on circuit-switched (PSTN).

• In the case of making a Fax-call to a PSTN subscriber, the GSM network automatically selects the suitable modem for the link to the similar modem at the remote end.

Teleservices

Teleservices

• Another service derived from telephony is voice messaging. Many operators offer it as a basic feature.

• It enables a voice message to be stored for later retrieval by the mobile recipient, either because he was not reachable at time of the call or because the calling party choose to access the voice mailbox of the GSM subscriber directly.

Supplementary Services

• Line Identification• Call Transfer and Call Forwarding• Waiting / Hold and Multi Party• Call Barring• Call Completion (CCBS)• Advice of Charge

Supplementary Services

Supplementary Services• Calling line identification presentation (CLIP) provides the ability to indicate the

number of the calling party with possible additional address information to the called party. This identity is provided to the called subscriber before answering, thus enabling him to make the decision of whether to take the call or not.

• Calling line identification restriction (CLIR) enables the calling party not to send any address information to the called party.

• Connected line identification presentation (CoLP) provides the GSM caller with the phone number he has reached.

• Connected line identification restriction (CoLR) enables the called party not to send its phone number to the calling party.

• Calling Name Presentation (CNAP) provides the calling party name instead of the ISDN number. However, this service is not yet specified by GSM recommendations.

Supplementary Services

Supplementary Services• Call forwarding unconditional (CFU) allows a called mobile subscriber to have the

network send all incoming calls, which are addressed to the called mobile subscriber’s directory number, to another directory number.

• Call forwarding on mobile subscriber busy (CFB): allows a called mobile subscriber to have the network send the incoming calls, which are addressed to the called mobile subscriber’s directory number and which meet mobile subscriber busy, definition to another directory number.

• Call forwarding on no reply (CFNRy) allows an called mobile subscriber to have the network send the incoming calls, which are addressed to the subscriber’s directory number and which meet no reply, to another directory number.

• Call forwarding on MS not reachable (CFNRc) provides for a mobile subscriber to have the network send all incoming calls, which are addressed to the called mobile directory number and meet the not reachable definition, to another directory number.

Supplementary Services

Supplementary Services

• Call waiting (CW): provides a mobile subscriber with the possibility of being notified of an incoming call while his mobile telephone is in the busy state. Subsequently, the user can either answer, reject, or ignore the incoming call. Both the call waiting and call hold (described further) options are the same as those offered by the PSTN.

• Call Hold (HOLD): allows a served mobile subscriber to interrupt communication on an existing call and then subsequently, if desired, to reestablish communication.

• Multi party service (MPTY):– This Supplementary Service provides a mobile subscriber with the ability to have a multi-

connection call, in other words a simultaneous communication with more than one party.– A precondition for the multi-party service is that the served mobile subscriber is in control of

one active call and one call on hold, both calls having been answered. In this situation the served mobile subscriber can request the network to begin the multiParty service.

– Once a multiParty call is active, remote parties may be added, disconnected or separated (i.e.. removed from the multiParty call but remain connected to the served mobile subscriber).

– The maximum number of remote parties is 5.

Supplementary Services

Supplementary Services• Barring of all outgoing call (BAOC): makes it possible for a mobile subscriber

to prevent all outgoing calls.• Barring outgoing international calls (BOIC): allows a mobile subscriber to

prevent all attempted outgoing calls.• BOIC except those directed to the home PLMN country (BOIC-exHC)• Barring of all incoming international (BAIC).• Barring of all incoming calls when roaming outside the home GSM network

country (BIC-Roam): makes it possible for a mobile subscriber to prevent all incoming calls that would otherwise be terminated at his directory number. This only applies to the case when the mobile subscriber roams outside his home GSM network.

Supplementary Services

Supplementary Services

• Completion of calls to busy subscribers (CCBS): allows a calling mobile subscriber who encounters a busy called subscriber to be notified by the system operator when the busy called subscriber becomes free and have the operator re-initiate the call if the caller so desires.

• This feature has to be supported by both the originating and the terminating networks.

Supplementary Services

Supplementary Services

• Advice of charge Information (AoCI): informs the user of the real-time information on progress of the cost of the call.

• Advice of charge Charging (AoCC): the mobile may be a money-operated mobile telephone or a standard mobile station that can display the charging information and can accept either coins or charge a credit-card.

Intelligent Network Services

• Main IN Services:– Personal Number– Virtual Private Network (VPN)– Sponsored Cell & Call– Prepaid Calling– Location Inquiry– Geo Zone

IN and CAMEL

Intelligent Network Services

• The aim of the CAMEL (Customized Application for Mobile network Enhanced Logic) is to provide GSM network operators with the ability to create specific services in their home network, and export these services to their subscribers when roaming outside the home network.

• CAMEL introduces the ability to provide location dependent IN type of services to mobiles subscribers.

IN and CAMEL

Intelligent Network (IN)• The Intelligent Network or IN is a switching network concept.• Its idea is to make GSM services system an open system; that is to say new services

modules can always be added on the previous system without changing its architecture.

• Basic call processing is performed by the switch and when it recognizes that a call requires an IN service, this service processing is provided by another entity, located either in the same site or in a remote site.

• This concept allows to implement numerous new services such as:– Personal Number: gives the GSM subscribers more control over incoming calls,– Virtual Private Network: a set of corporate services that enables similar functions to those of

private network, among a group of GSM subscribers,– Sponsored Cell and Call: allows a third party, as sponsor, to play announcement at the

beginning of the call,– Prepaid Calling: allows subscriber to pay in advance for the calls they will make.

Customized Application for Mobile network Enhanced Logic (CAMEL)

• To communicate between Intelligent Network platforms, GSM specifications define CAMEL (Customized Application for Mobile network Enhanced Logic).

• The aim of the CAMEL is to provide network operators with the ability to create specific services in their home network, and export these services to their subscribers when roaming outside the home network.

• CAMEL introduces the ability to provide location dependent IN type of services to mobiles subscribers: Location Enquiry and Geo Zone.

IN Services: Virtual Private Network

IN Services: Virtual Private Network

• Virtual Private Network (VPN) is a set of corporate services that enables private network like features among a group of GSM subscribers and wireline users; thus, corporations can distribute GSM phones to their employees, providing them with many of the services that they use on their existing corporate network:– Private Numbering Plan: subscribers can reach all members of the corporate

private network, GSM as well as wireline, by dialing their usual internal number instead of the longer, harder to remember, public number.

– Off Net Calling: subscribers are allowed to call public numbers that are outside the corporate private network.

– Forced On Net Calling: when a subscriber makes a call to a member of the corporate private network using their public number (he must also be provisioned with Off Net Calling), the feature recognizes the call as a private call and treats it as such (appropriate billing, etc.).

IN Services: Virtual Private Network

– White (/Black) List Screening: subscribers with White (/ Black) List, can only (/ can not) place calls to numbers listed on it.

– Geographic Routing: specific numbers can be configured to route calls differently depending on the location of the caller.

– Time Screening (/ Routing): some specific numbers can be configured to restrict access (/ to route calls differently) depending on the time of the day, day of the week, day of the year or whether the day is a statutory holiday.

– Privileged Routing: specific numbers can be configured to route calls differently depending on the identity of the caller.

– Closer user group (CUG): provides the possibility for a group of subscribers, connected to the GSM network and or to the PSTN/ISDN, to communicate only among themselves or receive external calls; emergency calls still are available.

IN Services: Prepaid Calling

IN Services: Prepaid Calling• Prepaid Calling enables subscribers to control their phone call expenditure, by

deciding how much to spend and limiting themselves to that amount if required.

• Subscribers pay in advance for their calls and get their calls released when the balance becomes null; thus, subscribers get a cost-control (useful for rental companies, hotels, special events, parents wanting to give mobiles to their children).

• With Prepaid Calling, subscribers are able to:– Make and receive calls (service is totally transparent to the subscriber during

normal use),– Be notified of a low balance or a pending expiry date (if the threshold is reached,

the subscriber can be notified by warning tones before the call is taken down),– Use Voice Mail,– Query the status of their account at any time from any phone and recharge their

account.

IN Services: Prepaid Calling• The subscriber can also be informed of his account balance and of the

cost of his last call, at the end of each call, via a short message.• Additionally, the Operator can apply different rates to calls and

manage the life of prepaid subscriptions.• Nortel’s prepaid solution currently supports all major recharging

options, for increased service usage and enhanced customer satisfaction:– Automatically, by vouchers (e.g. scratch card),– Automatically, by credit card,– Manually (through Customer Services), by any means of payment.

IN Services: Sponsored Cell & Call

IN Services: Sponsored Cell & Call

• Sponsored Cell & Call allows a third party (the sponsor) to play a promotional announcement at the beginning of a call and for this service, pays for part of the ongoing call.

• The main features of Sponsored Cell & Call are:• Choice to sponsor the call & choice of sponsor based on one or more of the following:

– The calling party location,– The calling party profile (age ...),– Time of day, day of week,– Destination (emergency, freephone ...).

• Sponsor can change his announcement on the phone.• User can specify certain destinations as not sponsored.• User can have the choice of having his call sponsored or not.• User can cut through the announcement, but the call is not sponsored.• User can be prevented from cutting through the announcement.

IN Services: Location Inquiry

IN Services: Location Inquiry

• Location Inquiry provides GSM subscribers with information on where to locate useful services in their current vicinity.

• It enables easy connection to any service they are interested in and wish to talk to.• However, while GSM subscribers are out of the office or away from home, they do not

have access to this information easily e.g. yellow pages, guides.• Most of time, they may be even more reliant on this information because they often

are in a foreign environment, e.g. in another part of town or out of town.• The Location Inquiry service brings in a third party known as the “Advertiser” who

seeks to sell their products/services using the operator’s network.• Location Inquiry may also list services such as hospitals, doctors, pharmacies, etc. and

be promoted as a personal security service.• The main features of Location Inquiry are:

– Location dependent information based on subscriber’s cell,– Possible customization of the announcement by the advertiser (special offer of the day...).

IN Services: Geo Zone

IN Services: Geo Zone• The main features of the outgoing side of Geo Zone are:

– Zone dependent tariffing of outgoing calls:• up to 4 zones per subscriber,• each zone has its own tariff,

– Information on the current zone available to the subscriber via:• announcement or tones at the beginning of the call,• optionally by a display on the mobile (in which case it must

support it, which means specific development on the handset).

IN Services: Geo Zone

IN Services: Geo Zone• The main features of the incoming side of Geo Zone are:

– Routing of incoming calls according to the subscriber’s location:• if the subscriber is in his Geo Zone, the call is routed to his mobile

handset, thus he does not have to pay anything,• if the subscriber is out of his Geo Zone, the call can be either routed to his

voice-mail, or to his mobile handset; in the last case the subscriber pays for the forwarding leg,

– Information on the current zone available to the subscriber, when receiving a call via:• announcement or tones before the call is connected.

Check Your Learning

1- What are the three categories of services defined in GSM?2- What are the two types of short messages?3- What are the two required pieces of equipment for data exchanges in

GSM (one in the MS, the other in the MSC)?4- What are the user data rates which were selected for GSM?5- What is the CLIP supplementary service?6- What is the CoLP supplementary service?7- What is the MPTY supplementary service?8- What is the call forwarding supplementary services?