词条 | Unstructured Supplementary Service Data | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
释义 |
USSD messages are up to 182 alphanumeric characters long. Unlike Short Message Service (SMS) messages, USSD messages create a real-time connection during a USSD session. The connection remains open, allowing a two-way exchange of a sequence of data. This makes USSD more responsive than services that use SMS.[1] UsesWhen a user sends a message to the phone company network, it is received by a computer dedicated to USSD. The computer's response is sent back to the phone, generally in a basic format that can easily be seen on the phone display. Messages sent over USSD are not defined by any standardization body, so each network operator can implement whatever is most suitable for its customers. USSD can be used to provide independent calling services such as a callback service (to reduce phone charges while roaming), enhance mobile marketing capabilities or interactive data services. USSD is commonly used by prepaid GSM cellular phones to query the available balance. The vendor's "check balance" application hides the details of the USSD protocol from the user. On some pay as you go networks, such as Tesco Mobile, once a user performs an action that costs money, the user sees a USSD message with his or her new balance. USSD can also be used to refill the balance on the user's SIM card and to deliver one time passwords or PIN codes. Some operators use USSD to provide access to real-time updates from social-networking websites like Facebook and Twitter.[2]{{better source|date=November 2017}} Wikipedia uses USSD to send articles to some feature phones.[3] USSD is sometimes used in conjunction with SMS. The user sends a request to the network via USSD, and the network replies with an acknowledgement of receipt: "Thank you, your message is being processed. A message will be sent to your phone." Subsequently, one or more mobile terminated SMS messages communicate the status and/or results of the initial request.[4] In such cases, SMS is used to "push" a reply or updates to the handset when the network is ready to send them.[5] In contrast, USSD is used for command-and-control only. Technical details {{Anchor|USSD for the GSMA aficionados}}Most GSM phones have USSD capability.[6] USSD is generally associated with real-time or instant messaging services. There is no store-and-forward capability, as is typical of other short-message protocols like SMS. In other words, an SMSC is not present in the processing path. USSD Phase 1, as specified in GSM 02.90, only supports mobile-initiated ("pull") operations.[7] In the core network, the message is delivered over MAP, USSD Phase 2, as specified in GSM 03.90.[8] After entering a USSD code on a GSM handset, the reply from the GSM operator is displayed within a few seconds. FormatA typical USSD message starts with an asterisk (*) followed by digits that comprise commands or data. Groups of digits may be separated by additional asterisks. The message is terminated with a hash symbol (#).[1] USSD ModeMobile-initiated
Network-initiated
Code table{{Off topic|date=September 2016}}The codes below are not USSD codes, but rather MMI Supplementary Service codes; they are standardized so they are the same on every GSM phone. They are interpreted by the handset first before a corresponding command (not the code itself) is sent to the network. These codes might not always work when using an AT interface; there are standard AT commands defined for each of these actions instead.[9][10]BS is the type of bearer service, some valid values are:
T is number of seconds for the No Reply Condition Timer, default is 20 seconds if not specified.
See also
References1. ^1 2 {{cite web|title=Unstructured Supplementary Services Data (USSD)|work=Telecom Space|accessdate=August 23, 2010|url=http://www.telecomspace.com/messaging-ussd.html}} 2. ^{{cite web |url=http://tech2.in.com/news/mobile-services/tata-docomo-introduces-facebook-twitter-access-via-ussd/230842 |last= Shetty |first= Anuradha |title=TATA Docomo introduces Facebook, Twitter access via USSD |date= 16 July 2011 |accessdate= 9 May 2013 |work=Tech2 |publisher=Network 18 India}} {{dead link|date=November 2017}} 3. ^{{cite web|url=http://blog.wikimedia.org/2013/02/22/getting-wikipedia-to-the-people-who-need-it-most/|last=Wadhwa|first=Kul|title=Getting Wikipedia to the people who need it most|date=22 February 2013|accessdate=10 May 2013|work=Wikimedia blog|publisher=Wikimedia Foundation}} 4. ^{{cite web|title=Monitor usage on your phone |accessdate=14 May 2012 |work=AT&T Residential Wireless Support |url=http://www.att.com/esupport/article.jsp?cv=820&sid=KB64693}} 5. ^{{cite web|title=Manage your account|url=http://www.att.com/esupport/article.jsp?sid=53414|work=AT&T Residential Wireless Support|publisher=AT&T|accessdate=11 May 2013}} 6. ^{{cite web|title=Windows Phone 7 doesn't support USSD|url=http://answers.microsoft.com/en-us/winphone/forum/wp7-wpstart/ussd-service/80ce77d9-5b46-4bbc-9a8f-c209f566f9a9|work=Microsoft Answers|publisher=Microsoft|accessdate=11 May 2013|date=8 February 2012}} 7. ^{{cite web|title=GSM 02.90 (ETSI TS 100 625, V7.0.0) Specification (USSD) – Stage 1|url=http://www.3gpp.org/ftp/Specs/html-info/0290.htm|work=3gpp.org|publisher=3rd Generation Partnership Project|accessdate=11 May 2013}} 8. ^{{cite web|title=GSM 03.90 (ETSI TS 100 549, V7.0.0) Specification (USSD) – Stage 2|url=http://www.3gpp.org/ftp/Specs/html-info/0390.htm|work=3gpp.org|publisher=3rd Generation Partnership Project|accessdate=11 May 2013}} 9. ^http://www.etsi.org/deliver/etsi_ts/122000_122099/122030/10.00.00_60/ts_122030v100000p.pdf 10. ^http://berlin.ccc.de/~tobias/mmi-ussd-ss-codes-explained.html External links
3 : Mobile telecommunications standards|3GPP standards|GSM standard |
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