In this article, we will learn how to answer a phone call using a GSM module and a computer. To answer a phone call, our GSM module should be interfaced with a speaker and headphones. We can purchase a Mikro C GSM development board, which has everything connected to it that we need to answer a phone call using a GSM module. We have already posted four articles related to GSM interfacing with computers, microcontrollers, and projects based on GSM. You can also check the following articles:
- GSM module interfacing with PIC microcontroller
- How to send SMS using GSM module and PIC microcontroller
- How to make a call using GSM module on any mobile number
- Wireless temperature sensor using GSM module
We recommend using the latest GSM module available in the market. We will be discussing the SIM900D GSM module in this article. The SIM900D GSM module has two microphones and two speaker connections. We can either interface speakers and headphones with the GSM module or we can purchase a ready-to-use GSM development board. The GSM development board should have speakers and headphones integrated with it, such as the Mikro C GSM development board. The microphone will be used to transmit our voice to the end user, while the speaker will be used to listen to the end user. The Mikro C GSM board also has amplifiers attached to the microphone and speaker to adjust the voice level.
How to Interface GSM Module with Computer
First, let’s start by exploring how to interface a GSM module with a computer to configure its settings. This step is crucial in ensuring the proper functionality and efficiency of the GSM module.
To begin with, I’ve explained in detail in a previous article titled “How to Make a Call Using a GSM Module on a Mobile Phone” on the Microcontrollers Lab website. This article provides a comprehensive guide on connecting a GSM module with a computer, highlighting the necessary steps and components involved.
To make the connection, you will need to follow a basic circuit diagram. This diagram serves as a visual representation of the connections required to establish a link between the GSM module and your computer. By carefully adhering to this schematic, you can successfully interface the two devices.
In the diagram, label 2 represents the GSM module which is connected to the MAX232 voltage level converter IC. Label 1 should be connected to the COM port of your computer. The MAX232 is a voltage level converter IC. The GSM module operates on 5-volt logic, while the computer’s serial port operates on 12-volt logic. Therefore, we need to use the MAX232 voltage level converter IC to ensure compatibility for serial communication between the two. After connecting the GSM module to the computer, follow the instructions below to answer a phone call.
SIM900A AT Command to Recieve Call
To answer a phone call using the SIM900A GSM module, you can use the following AT commands:
- AT+CHFA=1: This command is used to select the audio channel of the GSM module. In this case, it selects channel 1 of the GSM module.
- AT+CMIC=1,0: This command is used to select the gain of the microphones.
Once you have configured these commands, you will be able to receive phone calls and answer them using the following additional AT command:
- ATA: Type this command in the HyperTerminal and hit enter. This command will answer the incoming call, allowing you to talk with the person who called you.
If you want to end the call at any time, you can use the following AT command:
- ATH: Type this command in the HyperTerminal and hit enter. The call will be terminated.
To check the number of the caller, you can use the following AT command:
- AT+CLCC: This command allows you to check the number of the caller.
Remember to follow the instructions carefully and make sure your SIM900A GSM module is properly connected to your computer.
How to Answer Phone Calls Using a GSM Module
After connecting the GSM module, open the HyperTerminal of your Windows for serial communication with the GSM module. If your system doesn’t have the GSM module, you can download it from any website related to software. After opening HyperTerminal, write the following commands in HyperTerminal.
- “AT+CHFA = 1” is the command used to select the audio channel of the GSM module. 1 signifies the selection of channel 1 of the GSM module.
- “AT+CMIC = 1, 0” is used to select the gain of the microphones.
After that, whenever anyone calls the number which you used in the GSM module SIM jacket, you will see a message ring on the hyperterminal and the speaker will also emit a ringing sound. To answer a phone call using the GSM module, type the following commands in the hyperterminal.
- ATA type this command in Hyper Terminal and hit enter. Now you are ready to talk with the person who called you.
- ATH if you want to end the call at any time, you can type this command in Hyper Terminal and hit enter. The call will be terminated.
- AT+CLCC you can check the number of the caller using this command.
In conclusion, this article provided a comprehensive guide on how to answer a phone call using a GSM module and a computer. It emphasized the importance of interfacing the GSM module with the computer to configure its settings correctly. The article also highlighted the availability of ready-to-use GSM development boards such as the Mikro C GSM board, which integrated speakers and headphones for convenience. The instructions for answering phone calls using the GSM module in the HyperTerminal were clearly explained. By following the steps outlined in this article, readers can successfully set up their GSM module to answer phone calls and enjoy efficient communication.