If they really replied with,
Quote:I recied response 200 ok and message "INVALID SENDSMS CALL (WELCOME) "
Then I recommend leaving the platform as they leave no option of debugging or understanding what went wrong.
There are some ethics in HTTP programming (or Web API development), a 200 should be returned if everything goes fine and task has been accomplished—it can be a page load request, a record creation, etc.—but this Web API responds with a 200, but returns an error message and does not send anything.
You can try other products such as Twilio
]—I do not endorse the product—or you can try any other online SMS sending API, such as Alibaba Cloud SMS
] service if that makes sense to you.
You can learn more about Alibaba Cloud SMS service here, Connect to the World with Alibaba Cloud SMS (Short Message Service)