I will like to know if the SMS integration can be open so that individuals can add the company API they are using in the country they resides
Good question, this may depend on the API itself. Do you have a name or link to the service you're looking to integrate? We've added several SMS gateway options in v17, and there's flexibility to add additional gateways. If your service provides an SMS via email API this is supported now as well, and may allow integration without additional coding.