Module Across the world, we are all reliant on mobile communications as our primary way to communicate. Although we have all encountered situations when we were unable to answer our calls, they were either important personal calls or business calls that changed our lives. Due to the fact that you could not answer the call at that time, you might have missed that opportunity. A number of Arduino and GSM modules will be used in this project in order to create an Automatic Call Answering Machine to solve the problem. If you are switching to a new number or going on a long pilgrimage, remember this next time, or just record your voice stating your reason for absence while on vacation or enjoying a well-deserved break and Your recordings will be

automatically played to all the people on this machine when you call them. Your business numbers can also be used for answering customer calls during off-hours. Sounds interesting right? So let us build it.

Although it seems complicated, it is really easy to build, you just need the following components to get started Arduino Uno GSM module – Flyscale SIM 900 ISD 1820 Voice Module 12V adapter to power GSM module 9V battery to power Arduino Connecting wires Before we actually proceed into the project, let us get familiar with the GSM module and ISD 1820 Voice Module

Fig. Prototype of Automatic Call answering Machine using Arduino and GSM Module

GSM modules are extremely useful to us in our project, especially when we want to access the system remotely. In such a module, phone calls could be placed and received, SMS messages could be sent and received, and GPRS Internet connections could be made, for example. An USB-to-RS232 adapter is included with GSM modules, which can be plugged directly into a computer or to a microcontroller using either the TX or RX pins. A microphone or a speaker can also be connected to other pins besides MIC+

and MIC-. Power for this module can be provided by a 12V adapter through a regular DC barrel jack. Upon inserting your SIM card into the module, the LED should automatically become active. During the next minute or two, you will see a red (or other color) LED flashing every 3 seconds. Therefore, a connection was established between the Module and the SIM card. Getting started is easy once you have connected the module to a phone or microcontroller.

With the ISD 1820 Voice module, you can easily integrate voice announcements into your Projects. A 10 second audio clip can be recorded in this module, and you can play it when needed. An example of the device is shown below. The module comes with a microphone and a speaker (8- ohm, 0.5W).

Powered by berg sticks on the left, the modules operate on +5V. Rec, PlayE, and PlayL are the three buttons on the bottom of the screen. Click the corresponding button. Recording your voice is as simple as pressing the Rec button. By selecting PlayE, you will be able to play it. You can play the voice by pressing and holding the PlayL button. On the left, we see pins that are used to interface with a microcontroller. ESP8266/Arduino pins, which can handle 3V-5V, can act as direct drivers. In our project, we control the PLAYE pin on the Arduino module with the D8 pin.

The previous circuit diagram describes in detail this automatic voice call answering machine project. There are a lot of simple connections to be seen. The GSM module is powered by a 12V 1A adapter, while the Arduino runs on a 5V battery. We can play back our voice recordings on the voice module whenever we press the rec button on the voice module and then push P-E. In this case, the microphone of the GSM module will be used to capture the audio. Unlike the GSM module, the voice module has a microphone pin that is connected to the speaker pin on the GSM module. In order for the Arduino and the GSM module to communicate, you must use a serial connection. A chain is connected between the Arduino's X and Y

pins. In this way, Arduino will have the ability to communicate with the GSM module. The Arduino requests that the GSM module answer a call when it is received by the GSM module. The Arduino demonstrates that the call is active by turning pin 8 high for 200ms (connected to pins P-E on the voice module).