Discussion on Mobile Communication ussd business

From: http://www.cnblogs.com/pandengfeng/articles/1585068.html

 

Ussd (Unstructured Supplementary Service data) is defined
A mechanism for the Location Register (HLR) to transmit information and instructions. It provides a text-based interface for mobile communication users.
To manage users' business.

For example, if you enter "** 21*1234567 # Send" on your mobile phone, all the calls of this user will be transferred to the number.
1234567.

Both ussd and short message service (SMS) are transmitted through the network signaling channel. The difference is that short messages are stored and transferred
Sending method, and ussd is a dialog-oriented method. When a user accesses the ussd service, the conversation path remains connected until the conversation ends.
. In addition, you can access
Business nodes outside the GSM network.

In general, ussd has the following features:

(1) fast. In interactive applications, because only one connection is required, the delay for establishing multiple signaling connections is reduced.
The response time is shorter than that of the Short Message Service. The minimum response time is 1/7 of that of the short message;

(2) convenient. Instead of selecting a level-by-level menu, you can directly enter the ussd command string;

(3) supports roaming. Each Command of ussd must pass through HLR. Therefore, when a user is roaming
Running mode;

(4) It is widely used. What can ussd run on all current GSM mobile phones? (5) strong functions. Dialog and information
Provides services through the Business menu.

Ussd itself has some limitations: for example, the ussd command string is hard to remember. However, you can save the ussd strings of common services to your
Phone book to reduce memory and input difficulty. The ussd GSM standard consists of three phases:

(1) The earlier ussd phase1 only supports operations initiated by the Mobile Station.

(2) The current ussd Phase 2 standard further supports operations initiated by the network and can be performed on mobile platforms and network nodes.
Establish a dialog between them, and then perform multiple subsequent operations on the dialog.

(3) The European Telecommunications Standards Commission (ETSI) is considering the enhanced ussd standard-ussd phase2 + in the future, including
Supply: digital encoding DCS, used to distinguish between MMI mode and bearer mode: replacing character-form business code with binary encoding
(Service Code), used to determine network routes; Introduce the UDH (user data header) concept in short messages (see
Gsm03.04); supports multiple dialogs at the same time.

1. Working Mechanism

1.1 The Mobile Station initiates a conversation. The mobile station sends a "Call: Process ussd requests" request to initiate a conversation, which can be sent over the network.
"Ussd response" or "result: Processing ussd request" is returned to release this conversation. The mobile station or network can be in any
Send the layer-3 wireless message rekease complete to release the dialog.

1.2 initiate a dialog network call ussd request operation, initiate a dialog, and the mobile station returns the result. Either party can
Send the release complete at any time to release the dialog.

1.3 operation parameters each ussd operation has two parameters: data encoding mode DCS and ussd string, the former specifies the latter
Data encoding method. According to gsm02.90, the DCS must be set to "Language
Unspecified and default alphabet ". According to gsm03.38, It is encoded as oxof (Binary 0000
1111 ). According to gsm03.90, if the DCS value is inconsistent with the standard value, the network should reject the operation.

1.4 ussd string when ussd acts as a full-duplex data packet transmission mechanism, the message structure is the same as that of SMS. In SMS
The user data segment can be composed of a short message itself or a message header (UDH) attached. Defined in gsm03.40: UDH includes
One or more metadata (ie, information element ). An IE consists of three fields: Tag
(Identifier), length, and content (data ). The cell structure defined in cism03.40 is as follows: Cell tag
Iei (1 byte), defined by gsm03.40; cell length (IEL) 1 byte, indicating the length of the cell content; cell content
(Iei) 1 to n Bytes, indicating the information content carried by the cell. The Service Code (serve Code) is a specific parameter of the network operator.
Number, used to mark network nodes. The user must enter the Business Code to call a service, such as the string "* # SC * n
In characters #, SC indicates the Business Code. The first ussd string sent by the mobile device must contain a Business Code and is responsible
Directs the string to the target node to establish a dialog between the mobile platform and the network application. In subsequent operations
Service Code. Two types of business codes are marked in gsm02. the former directs the ussd string to HLR, and the latter
MSC/vlr. If the final application is outside the GSM network, the ussd application on the HLR serves as the intermediary to send the received
The ussd operation is converted and passed to the final application. The maximum length of the ussd string is related to the Operation Type and is also limited.
Capacity configuration of TCAP messages on the Signaling Layer: Sub-network calls of mobile platforms: Processing ussd requests (initiating a dialog between mobile devices), 133 words
Result of connecting the network to the mobile station: 160 bytes for processing ussd requests (initiated by the mobile station); calls from the network to the mobile station:
Ussd requests (initiated by the mobile device), 154 bytes; calls from the network to the mobile device: ussd requests (initiated by the Network), 144
Byte; Result of the mobile station to the network: ussd request (Network-initiated DIALOG), 154 bytes; Other information: 160 bytes.

1.5 In order to monitor the ussd dialog and prevent the dialog from being suspended, the operation of each body starts the corresponding Timer:

(1) The "processing ussd requests" timer is enabled when the network receives the "processing ussd requests" until the network
Send the "processing us SD request result" dialog to the Mobile Server for release. The timer limits the total length of the dialog to 1-
10 min.

(2) "Call: ussd request" timer when the network sends a "Call: ussd request", start the exit tool
Received "Result: ussd request ". The timer limits the processing time of the mobile application to 1 ~ 10 min (including the user's screen
Information, and press the time ).

1.6 There are two kinds of network addressing ussd business addressing methods:

(1) use the service code to directly address ussd nodes and external business nodes;

(2) The business code is only responsible for guiding to the ussd node, and then according to the address carried in the ussd string, the node is directed to the business
Service node. This feature enables users to access multiple external business nodes in a dialog, provided that
All operations must carry the addresses of external business nodes (such as the IP addresses of business book points ).

2. Application Status

Ussd is not widely used in China (except Hong Kong), but has been used in Hong Kong and abroad, for example: Hong Kong
Digital connect uses the SMSC and ussd gateways of semavision to implement the "smartinfo" business. Users enter specific ussd
Business code, and then use short messages to receive information such as stock trading and foreign exchange trading. Vodafone in the UK uses ussd to set and
Cancel unconditional call forwarding. About 10 network operators in Sweden use their SIM card application platforms.
(Sicap), which is a ussd-based prepayment roaming solution (GSM card easy roam): used for roaming
After the user sends the outgoing call number to the sicap through the ussd string (* 101 * + 4470003 66366 #), The sicap calls the number back.
And connect the user to "4471000366366. Currently, ussd-based telecom products mainly include: (1)
Sema vision ussd gateway of Sema group, which has been used by digital connect Hong Kong to commercialize and put into operation
Platform;

(2) The ussd server provided by Logica aldiscon adopts the smpp (Short Message Peer to Peer) protocol.
As an application interface, it supports interaction with SMS and provides configurable routes;

(3) Ericsson's webonair platform supports multiple protocols, including SMS, ussd phase2, and WAP;

(4) The Nokia artusussd center provides dedicated API interfaces.

3 Market Prospects

With the development of Telecom Reform and the approaching period of entry, the domestic telecom market will gradually open up. Ussd technology is used independently or
The current combination of short message technology and GPRS technology can provide customers with a wide range of value-added services, such as information services, mobile
Bank calls to e-forums through mobile platforms, which has broad market prospects.