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 🙂

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
• Get SMS Status Report (delivery status)
• 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
• SMS Status Report 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:

using HeboTech.ATLib.Messaging;
using HeboTech.ATLib.Misc;
using HeboTech.ATLib.Modems;
using HeboTech.ATLib.Modems.Adafruit;
using HeboTech.ATLib.Numbering;
using HeboTech.ATLib.Parsing;
using System;
using System.IO.Ports;
using System.Threading.Tasks;

namespace HeboTech.ATLib.TestConsole
{
    public class GetStartedExample
    {
        public static async Task RunAsync(string portName, int baudRate, string pin, string recepientPhoneNumber)
        {
            // Set up serial port
            using SerialPort serialPort = new SerialPort(portName, baudRate, 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);

            // Listen to incoming SMSs
            modem.SmsReceived += (sender, args) =>
            {
                Console.WriteLine($"SMS received: {args.SmsDeliver}");
            };

            // Listen to incoming SMSs stored in memory
            modem.SmsStorageReferenceReceived += (sender, args) =>
            {
                Console.WriteLine($"SMS received. Index {args.Index} at storage location {args.Storage}");
            };

            // 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}");

            // Check if SIM needs PIN
            if (simStatus.Result == 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();

            // Read SMS at index 1
            var sms = await modem.ReadSmsAsync(1);
            if (sms.Success)
                Console.WriteLine(sms.Result);

            // Send SMS to the specified number
            PhoneNumber phoneNumber = PhoneNumberFactory.CreateCommonIsdn(recepientPhoneNumber);
            string message = "Hello ATLib!";
            var smsReferences = await modem.SendSmsAsync(new SmsSubmitRequest(phoneNumber, message));
            foreach (var smsReference in smsReferences)
                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.