Maybe we solved the problem. We started to use another api and filled headers (didn't do that before).
Now we can send long messages well.

I found some kind of stack in the system event viewer.

Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.OverflowException
Stack:
at System.Convert.ToByte(Int32)
at Inetlab.SMPP.PDU.SubmitSm.wVmyuruuum()
at Inetlab.SMPP ...

We don't have a stack, because our service just crashes. If I debug it, I have the following:

System.OverflowException was unhandled
Message: An unhandled exception of type 'System.OverflowException' occurred in mscorlib.dll
Additional information: Value was either too large or too small for an ...

Hi All!
We are using your lib to send sms to our clients. Today we met a terrible problem. When we call the SubmitSmResp Submit(SubmitSm pdu) method our service crashes totally.
We investigated it and found out that the problem is in sms longer than 127 symbols. 127 symbols sms is ok.

Then we found ...