what is the purpose of using USSD Commands in our J2ME Application? Is this possible?

I heard the开发者_StackOverflow中文版re is USSD Commands in Mobile.But i dont know what it is? i was googling two more sites.i did not understand it.Please anybody having knowledge about USSD Commands, share with me.

How it is useful when we using USSD Commands with our j2me midp 2.0 application development?

Please suggest me some useful URL's to get this properly.

Also, i would like to here about AT Commands too?

Thanks & Regards, P.SARAVANAN

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USSD is Unstructured Supplementary Service Data.

GSM standardizes on the syntax (i.e. message transport) of USSD but not on the semantics (i.e. what one can do with USSD is network-operator-specific).

USSD applies a request/response pattern. A user sends a USSD request which is processed by the network and eventually answered with an USSD reponse. In a nutshell, USSD allows an end user sending numerical commands. These commands are transported by protcol functionality within the SS7 signalling stack from the mobile device to the mobile network MSC (mobile switching center, the nework node controlling the mobile network). The network operator configures the MSC to handle specific USSD requests, typically to forward them to various other network elements. Among them are:

• HLR (home location register, the user database) to switch on/off telephony services.

• IN (intelligent network, the realtime billing platform, among others) voucher management system for prepaid top-up.

• USSD gateway to branch out USSD messages to external systems.

These network elements then generate USSD responses which are transported back to the user.

Using USSD from J2ME is offered via:

• Devices supporting JSR 120 (Wireless Messaging API). Consult manufacturers development documentation or device databases to check which devices are covered.

• AT command (AT+CUSD) via serial interface emulation.

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The user composes some message—usually rather cryptic—on the phone keyboard.

The phone sends it to the phone company network, where it is received by a computer dedicated to USSD. The answer from this computer is sent back to the phone. The answer could be seen on the phone screen, but it is usually with a very basic presentation.

The messages sent over USSD are not defined by any standardization body, so each network operator can implement whatever it finds suitable for its customers.