I have developed a app for PLCnext called PLCnextBot that allows integrating PLCnext controllers to the Telegram messaging service, allowing the sending of text messages, such as alarm or event information, to Telegram app.
The app is a function extension, developed in C++. It will monitor Out Port Variables from PLCnext and when the rising edge of these variables is detected, a text message is sent to all Telegram users registered in the app. The app configuration is done by a json file.
This app can be used as an easy and cheap substitute solution for applications that require SMS message.
I have shared this app via PLCnext Store where you can find a manual with more details. (https://www.plcnextstore.com/#/605)
I hope this app can be useful to you.