Send Bulk OTP SMS in PHP using SMS Gateway Center HTTP API
You need to be registered member with https://www.smsgatewaycenter.com/ and then you can use this script to send OTP SMS to your clients and peers.
This script is just an example to send sms and validate OTP using session. But you can use it with your database to get users and send out OTP SMS to registered members and have them validated.
About SMSGatewayCenter.com SMS Gateway Center is one of the leading Bulk SMS Gateway...
This is a simple and easy to modify PHP form, which will allow you to send SMS messages through HTTP with your own Sender ID and delivery reports. You just have to insert your account information (www.sourcesms.com) and upload the files onto your web server.