Hi there, I'm a Delphi developer with 10 years experience in Windows and web development (multiple tools and languages). I happen to have developed an SMPP client that has been deployed at 2 GSM operators.
I have tested my SMPP client successfully using desktop simulators (Java-based) and live network environments (Ericsson and Siemens-based networks running Comverse, ZTE and Intervoice Bright SMSCs). I have implemented SMPP versions 3.3 and 3.4 and am well versed with the protocols, as well as the trickier issues you're likely to confront when you deploy onto a live network.
I am able to test your SMPP client using my desktop simulator, and if necessary, test against a live SMSC. On a live environment, I can guarantee access to a 3.3 interface, but 3.4 would have to be confirmed as it may require talking to the vendor. I only have direct relationships with the operators.