Custom SMS texts API

I have an API that I want to use as a substitute for the plugins used to send sms in os service booking.. This is a better alternative in my use case based on country and the sms charging rates and I would like to inquire how I can set up the api so that I can use it to send sms in Os Service Booking.
Thanks

Hi Rodgers,
OS Services Booking has different SMS plugins, you can find them in folder: plugins -> osservicesbooking, for example: OS Services Booking Booking SMS - Clickatell
You can check the code of those plugins and implement for your SMS service provider.
Thanks
Dam