ATLib

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.

Feedback is very much welcome and please request features 🙂

HeboTech.GsmApi is a REST API wrapping this library.

Supported commands:

• Send SMS in PDU format (GSM 7 bit or UCS2 encoding)
• Send concatenated SMS (message that spans over multiple SMSs) in PDU format (GSM 7 bit or UCS2 encoding)
• SMS supports emojies
• List SMSs
• Read SMS (PDU format (GSM 7 bit or UCS2 encoding))
• Delete SMS
• 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 / set date and time
• Disable echo
• Send USSD code
• Get / set character set
• Get IMSI
• Some modems may also support modem specific commands

Events

• Incoming call
• Missed call
• Call started
• Call ended
• SMS received
• Error received
• USSD response received
• Generic event

Supported modems:

• 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)
• Cinterion MC55i
• Other modems may work using one of the implementations above. You can add your own implementation using the existing functionality as base.

Other

• Debug functionality that lets you intercept incoming and outgoing data

Usage

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 = AtChannel.Create(serialPort.BaseStream);

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

// Open AT channel
atChannel.Open();

// Configure modem with required settings before PIN
var requiredSettingsBeforePin = await modem.SetRequiredSettingsBeforePinAsync();

// 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}");
}

// Configure modem with required settings after PIN
var requiredSettingsAfterPin = await modem.SetRequiredSettingsAfterPinAsync();

// Send SMS to the specified number
var smsReference = await modem.SendSmsAsync(new PhoneNumber("123456789"), "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.