Some SMSC does not support SubmitMulti. Please ask them if this message allowed to you.

I found out that to be the case in my situation. Thanks for the heads up. I also noticed that the client automatically generates a value for the Sequence property. That's proactive.

Thanks for the prompt ...

I tried using Submit with SubmitMulti, but the only response is GENERIC_NACK. My code is in Boo (http://boo.codehaus.org), a Python-like .NET language. I'm using the interpreter, and also copied the output (output lines DO NOT begin with >>>:

>>>import ALT.SMS
>>>c = SmppClient()
ALT.SMS ...