Hi, I'm a Delphi developer with more than 35 years of experience (yes, since the times of Borland Turbo Pascal). I'm sure I can help with your project, and provide you the basic code to read and send sms messages through Plivo. Note that the Plivo's API is based on HTTPS messages, so the Delphi code would mainly be dedicated to send, receive and decode these HTTP messages to the Plivo server.
If you think you may be interested in my services, please send me a message, we can further discuss the details of your requirements and I can provide a copy of my CV for you to check references and experience.
Best regards,
Marco García