Hello,
I'm a software engineer and PHP expert , I've done this before, so i can provide you with a campaign management systems, ready to be used, I developed this system specifically to manage sms campaigns, you can edit the 'STOP' keywords and set various commands for each campaign, it comes also with a dashboard that lets you chat with your prospects by sending sms directly from this tool.
Please note that I'm willing to adjust this system to your needs, to do so I need you to provide me with the SMS gateway you're using (twilio, Nexmo, messagebird, or any other).
At first we will discuss the requirements, later I will need a day and a half to apply the changes and get back to you.
you will be provided with a complete solution within 2 days.
Looking forward to hear from you.
Cordially, Marwen