C# SMS sending issue

Question

Hello friends!

I have an urgent question.

I am a beginner and I was trying to send SMS in C#. I found this C# SMS solution, however I could not make it work. The message was not showing in the SMS Gateway after I sent it. I must have missed some settings but I cannot figure out what.

I used the code shared here. 

 

I could really use some help.

Thanks in advance.