These API files are tested under PHP 8.1.6, they aim to demonstrate how to send out SMS through HTTP API.
The files version are 1.3.

During the https transmission, if you get the error 
"SSL routines:tls_process_server_certificate:certificate verify failed", 
it usually means that PHP cannot find or trust the Root Certificate Authority (CA) bundle needed to 
verify a secure connection. Please follow the steps below to solve it:

1. Download an Updated Certificate Bundle 
- PHP requires a .pem file containing the latest trusted root certificates. 
- Download the latest cacert.pem from the official Curl site.
Ref https://curl.se/ca/cacert.pem
- Place it in a directory accessible to PHP (e.g., C:\php\extras\ssl\cacert.pem for Windows)

2. Configure PHP to Use the Bundle
- You must tell PHP exactly where this file is located by editing your php.ini file.
- Locate your active php.ini file (run php --ini in your terminal to find it).
- Search for the [openssl] and [curl] sections and update these lines 
(remove the ; at the beginning to uncomment them):

-------------------------------------------------
[openssl]
openssl.cafile="C:\php\extras\ssl\cacert.pem"

[curl]
curl.cainfo="C:\php\extras\ssl\cacert.pem"
-------------------------------------------------

3. Restart Your Web Server
After saving changes to php.ini, restart your web server (e.g., Apache, Nginx, or IIS) for the settings 
to take effect. 

