what does ussd code mean

ussd is the unstructured supplementary data service. It is a new type of interactive data service based on the GSM network. Use the mobile phone keyboard to enter some numbers or symbols that have been predetermined by the network, such as "*#", etc., and then press Send is a dial key that can send an instruction to the network. The network will select the service you need and provide it to you based on your instruction.

#The operating environment of this article: windows10 system, thinkpad t480 computer.

What does the ussd code mean?

This is a problem caused by smart dialing. The number you dial starts with * and ends with #. The phone thinks you are sending a USSD code, so it shows that the USSD code is running. If the mobile network you are using supports USSD, an error message will be returned. If it does not, it will remain dead.

USSD (Unstructured Supplementary Service Data) is an unstructured supplementary data service. It is a new type of interactive data service based on the GSM network.

When you use the mobile phone keyboard to enter some numbers or symbols that have been pre-set by the network, such as *#, etc., and then press send, which is the dialing key, you can send an instruction to the network, and the network will select the one you need based on your instruction. Services provided to you.

Compared with short messages, GPRS and WAP, its feasibility and advantages in industrial applications are described. Taking the wireless remote monitoring system successfully operated by China Electronics Fifty Research Institute in Urumqi as an example, the USSD is used in System architecture, interface protocols and communication processes in industrial applications.

Extended information:

USSD features:

1, call status

Use the independent dedicated control channel SDCCH (Stand-alone Dedicated Control Channel), the data transmission rate is about 600bps; when not in the call state, USSD uses the fast auxiliary control channel FACCH (Fast Associated Control Channel), the data transmission rate It is about 1kbps, which is higher than SMS transmission rate.

Users can only use WAP when not in a call state. Data is exchanged through the TCH (Traffic Channel). The transmission rate is about 9.6kbps. The response time of WAP is slow and a special WAP mobile phone is required. support.

2, the conversation process

always maintains the call connection, provides a transparent channel, and does not store and forward; while SMS does not have a session channel at the physical bearer layer, it is a store and forward system, users need to complete multiple sessions to complete a query. Since USSD is similar to GPRS, a session process is maintained during the interaction. Each data transmission does not require re-establishing the channel. Therefore, the USSD system responds to the user's call request immediately, greatly speeding up the response time. The main response delay has been transferred to On the application server side, the response time is faster than short messages.

3, interactive session

can provide intuitive menu operations to facilitate users. In an information service, you only need to dial the service number, and you can press The menu prompts for the next step. You can establish a portal similar to WAP to provide telecommunications value-added services.

4, user group

In an industrial environment, the cost of using USSD is low when the communication volume is not large and each communication volume is only a few K of data. ; GPRS transmission bandwidth is high and suitable for data transmission with large amounts of information.

Most mobile phones on the market support USSD services

In industrial applications, most communication modules or chips with SMS and GPRS functions also support USSD services.

5, system structure

The monitoring center establishes a TCP/IP connection with the USSD platform through the Internet or a dedicated line, and the USSD transmission terminal establishes a wireless connection with the USSD platform through the GSM public network. Connection, establishing a data communication channel with the GSM network, monitoring center and on-site monitoring unit through the USSD platform.

There is database backup data in the mobile USSD platform. In addition to the application platform, the monitoring center can also be equipped with a wired browser for monitoring. Through the GSM network and USSD platform, wireless browsers and mobile phones can also establish contact with the monitoring center.

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