SMS API Integration in WordPress website

Question

WordPress is the platform I am using, and I want to integrate an SMS API into it. Can anyone help me with knowing where (in what file) to write the code for integrating SMS API and also where to write the code for a welcome SMS when a new user registers on-site? After approval, a second SMS should be sent automatically. I am using the ultimate plugin in WordPress. I am using SMSala Gateway API Service

URL: https://smsala.com

You can find my API URL here.

Send Single SMS to URL: https://smsala.com/api/mt/SendSMS?user=xxxxxx&password=xxxxxxxx&senderid=xxxx&channel=xxx=0&flashsms=0&number=xxxxxxxx&text=xxx&route=xx

Answer 1

https://smsala.com/docs/#idocs_calling_the_api

Have a read