We want to develop a new SMS gateway service from scratch for our new Product and we are looking for the same product like Twillio and any other SMS service that allow user to send international SMS.

We have no idea how to do that and what technology and expertise needed to do that.. please help if any one know about how to do this.

Thanks in advance

A few years ago I went to the CTIA convention (google Super Mobility 2016) and ATT would send messages by the tens of thousands for 10 to 20 bucks. This laid waste to the cost of how much to build your own systems. Not only that but you didn't have to have a database of numbers to send to. ATT has a database that you select your targets and then they send to those folk.

I'm sure other carriers do this as well.