ATLib is a C# AT command library that abstracts away the commands and makes it easy to communicate with modems.

Hayes command set (commonly known as AT commands) is a command set frequently used in modems. Read more about it at Wikipedia.

ATLib is just in the beginning. Currently only a few commands are implemented, but more will come.

HeboTech.GsmApi is a REST API wrapping this library.

Feedback is very much welcome 🙂

• Send SMS
• List SMSs
• Read SMS
• Delete SMS
• Set SMS message format (to text)
• Dial number
• Answer incoming call
• Hang up call
• Get SIM status
• Enter SIM PIN
• Get remaining PIN & PUK attempts
• Get product information
• Get battery status
• Get signal strength
• Get date and time
• Set date and time
• Disable echo
• Some modems may also support modem specific commands

• Incoming call
• Missed call
• Call started
• Call ended
• SmsReceived (not fully implemented)

• Adafruit FONA 3G (based on SIMCOM SIM5320 chipset)
• D-Link DWM-222 (based on Qualcomm MDM9225 chipset)
• TP-LINK MA260 (based on a Qualcomm chipset)

• Other modems may work using one of the implementations above

Install as NuGet package

dotnet add package HeboTech.ATLib

Using a serial port to communicate with a modem is easy:

// Set up serial port
using SerialPort serialPort = new SerialPort(args[0], 9600, Parity.None, 8, StopBits.One)
{
    Handshake = Handshake.RequestToSend
};
serialPort.Open();

// Create AT channel
using AtChannel atChannel = new AtChannel(serialPort.BaseStream);

// Create the modem
using IModem modem = new Fona3G(atChannel);

// The library doesn't support echo, so turn it off
await modem.DisableEchoAsync();

// Get SIM status
var simStatus = await modem.GetSimStatusAsync();
Console.WriteLine($"SIM Status: {simStatus}");

if (simStatus == SimStatus.SIM_PIN)
{
    var simPinStatus = await modem.EnterSimPinAsync(new PersonalIdentificationNumber("<PIN>"));
    Console.WriteLine($"SIM PIN Status: {simPinStatus}");
}

// Send SMS to the specified number
var smsReference = await modem.SendSMSAsync(new PhoneNumber("0123456789"), "Hello ATLib!");
Console.WriteLine($"SMS Reference: {smsReference}");

Because it relies on a stream, you can even control a modem over a network! Either use a network attached modem, or forward a modem serial port to a network port.

For more examples, check out the TestConsole project in the code.