Revision as of 22:25, 23 May 2008

Good to know before reading the rest of this article

Different phones support different sets of AT commands. So not all AT commands listed below might not be supported by a specific phone. Currently there is no authoritative list available of supported AT commands by all phones.

Overview

AT commands are also known as Hayes AT commands. There are different views to understand the meanings of "AT". Some people call it as "Attention Telephone" or some people call it as "Attention Terminal" commands.

AT commands allow us to give instructions to a phone, either a mobile phone or a normal landline telephone. The commands are sent to the phone's modem, which can be GSM modem or PC's modem. In this discussion, we will focus on AT commands on Nokia's GSM and WCDMA products only. Different manufacturers may have different set of AT commands. Fortunately, many AT commands are the same. Mobile manufacturers may also give attention to operators to allow or not to allow some commands on the phone.

Let us see in brief the usage of AT commands. We can perform operations that we normally do from the keypad, for instance calling a number, sending an sms, reading an SMS, deleting an SMS, setting the SMSC number, looking for GPRS access point, reading phonebook data, deleting phonebook data, reading the battery status, reading the signal strength etc. When we want to make a PC based application to interface a mobile phone using USB, IR or bluetooth, such commands are needed to communicate with mobile phones. Basically such commands are application layer of MBUS or FBUS commands. Nokia provides an AT command set guide by which we can refer the basic command syntax and the response of the command in various situations (see Related Links section at the end of this article).

Using AT Commands with HyperTerminal

Let us see now how to use AT commands. The AT commands work on device that has built-in GSM modem. If it exists, there is no need of virtual modem software to install on your PC. If you are using very older Nokia phones you have to find out the DATA suite not the PC Suite for such phones (Nokia 5110) to use AT commands. We will focus on the mobile phones which has built-in GSM modem.

Follow the instructions below on your PC to use AT commands:

• Connect your mobile phone in PC Suite mode using any available connection (BT, USB or IR).

• Make sure that you have installed proper GSM modem driver on your PC. You can check it from Control Panel | System | Hardware | Device Manager. Check Modems section. If you see something like "Nokia XY USB Modem" or "Nokia XY Bluetooth Modem", it means the device has built-in GSM modem. If you don't have it, go to Nokia web site and download the driver from the product page of your device.

• Open the HyperTerminal, a communication utility on your Windows OS. You can find the HyperTerminal in Start | Programs | Accessories | Communication.

• Create a new connection set on HyperTerminal. You may need to set some of the parameters, such as baud rate (normally 9600), handshaking mode (Xon-Xoff), parity bit (default) etc.

• Select the communication port on which your mobile has been connected. once you are done with this you can give the basic AT command, type simple AT in the window so you will get "OK" response.

There are basically two modes to work for mobile phones. one is PDU and another is text mode. PDU is protocol data unit. Mobile normally understands internally in PDU format. We can use both. AT+CMGF is the command to set the mode. If we type AT+CMGF=0 the PDU mode is set. If we type AT+CMGF=1 the text mode is set. If we want to check which mode has been set we can type simple AT+CMGF? so it will show the result.

Now for example we want to dial out a number called "111" the command is ATD 111 or ATD "111".

To send an SMS first we have to set the mode in text. We can send SMS in both the modes but the format of typing text to send SMS is different. For normal usage we use text mode. So type AT+CMGS="9198XX21XX99", "Message" ^ctrlZ. So SMS will be sent out from your PC through mobile phone. To read an SMS from the inbox we have to write AT+CMGR=1 to read the sms stored at 1st location. The location starts from 0 so be careful. To delete an SMS type AT+CMG

NOKIA GSM AT COMMAND SET

Call Control

Data Card Control Commands

Phone Control Commands

Computer Data Card Interface Commands

Service

Network Communication Parameter Commands

Miscellaneous Commands

SMS Commands SMS Text Mode

SMS PDU Mode

Related Links

• AT Command Set For Nokia GSM And WCDMA Products v1.2
• AT Command Set For Nokia GSM Products
• Sending_AT_Commands example source codes