CometTextel.NET 1.2.0

CometTextel.NET

.NET wrapper for the CometTextel GSM SMS library (comettextel.dll).
Send / list / delete short messages over a serial modem, or encode / decode PDU hex without hardware.

Requirements

x86 / Arm64 processes cannot load the bundled 64-bit native DLL.

NuGet

PM> Install-Package CometTextel.NET

Consumer projects must target Windows x64 so comettextel.dll can load.

Important notes

Concatenated SMS

Pdu.EncodeSubmit is single-segment (fails if the payload is too long).
Pdu.EncodeSubmitSegments and GsmModem.Send auto-split with concat UDH (IEI 0x00, ≤ 255 parts).

Payload caps: single GSM 7-bit ≤ 160 / 8-bit·UCS-2 ≤ 140; concat GSM 7-bit ≤ 153 / 8-bit·UCS-2 ≤ 134.

On receive, if TP-UDHI is set, the UDH is skipped (HasUdh == true). Concat IEI 0x00 / 0x08 populate IsConcatenated, ConcatRef, ConcatTotal, ConcatSeq. Multi-part messages are not reassembled.

Strings

All text fields are UTF-8 at the native boundary (LPUTF8Str / UTF-8 byte fields). Prefer ASCII digits for SMSC / destination addresses.

Native lifetime

GsmModem owns a native handle. Always Dispose() (or using) when finished.
Do not use an instance after dispose.

Errors

Failed native calls throw CometTextelException with a numeric Status (ct_status) and message from ct_status_string.

Quick start

PDU only (no modem)

using CometTextel.NET.Core;

string hex = Pdu.EncodeSubmit(
    destination: "886912345678",
    text: "Hello from CometTextel.NET",
    serviceCenter: "886932000000",
    coding: DataCoding.Ucs2);

Console.WriteLine(hex);

SmsMessage decoded = Pdu.Decode(hex);
Console.WriteLine(decoded.PeerAddress + " => " + decoded.UserData);

Send / list / delete

using CometTextel.NET.Core;

using var modem = new GsmModem();
modem.Open("COM3", baudRate: 115200);

modem.Send(
    destination: "886912345678",
    text: "Hello",
    serviceCenter: "886932000000",
    coding: DataCoding.Ucs2);

foreach (var message in modem.List())
{
    Console.WriteLine($"[{message.Index}] {message.PeerAddress}: {message.UserData}");
}

// modem.Delete(index: 1);

Smoke tests

Requires CometTextel.NET/Lib/comettextel.dll (same as packing):

dotnet test CometTextel.NET.Tests\CometTextel.NET.Tests.csproj -c Release -p:Platform=x64

pack.ps1 and Windows CI run these before producing the NuGet package.

Examples project

From nuget/CometTextel.NET (after pack.ps1 or a native Release build that copied Lib/comettextel.dll):

dotnet run --project CometTextel.Example -c Release -p:Platform=x64 -- pdu 886912345678 "Hello" 886932000000
dotnet run --project CometTextel.Example -c Release -p:Platform=x64 -- list COM3
dotnet run --project CometTextel.Example -c Release -p:Platform=x64 -- send COM3 886932000000 886912345678 "Hello"
dotnet run --project CometTextel.Example -c Release -p:Platform=x64 -- delete COM3 1

Build & pack

Requires CMake + MSVC (for comettextel.dll) and .NET SDK 8+ on Windows.

# From repository: comettextel/nuget/CometTextel.NET
.\pack.ps1

This script:

1. Configures/builds the C++ library (COMETTEXTEL_BUILD_C_API=ON, win-x64 Release)
2. Copies comettextel.dll into CometTextel.NET/Lib/
3. Runs dotnet pack and writes .nupkg under artifacts/

Manual steps (native DLL must already be in CometTextel.NET/Lib/):

dotnet build CometTextel.NET.sln -c Release -p:Platform=x64
dotnet pack CometTextel.NET\CometTextel.NET.csproj -c Release -p:Platform=x64 -o artifacts

API surface (summary)

Namespace: CometTextel.NET.Core.

Native C ABI (inside comettextel.dll): ct_modem_*, ct_pdu_encode_submit, ct_pdu_decode — see include/comettextel/c_api.h in the C++ tree.

License

Copyright (c) 2026 Ji-Feng Tsai.
Code released under the MIT license.

TODO

• Concatenated SMS reassembly APIs
• Optional linux-x64 NuGet RID assets

Donation

If this application help you reduce time to coding, you can give me a cup of coffee 😃

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