Answer 1

When using SMS php Api there are some things you have to consider

1, Which framework (codeigniter, laravel sympony etc) you are using, to build your SMS Form and also its dependencies like curl in php has to be installed

2.SMS Gateway (An SMS gateway allows a computer to send or receive Short Message Service (SMS) transmissions to or from a telecommunications network. Most messages are eventually routed into the mobile phone networks. Many SMS gateways support media conversion from email and other formats.).

Some are free (open source but does not work for all countries) and some are paid (good ones) which if registered you will be given docs on how to include their API to your code to make your website send SMS.