SOAP Webservices using the NuSOAP library
As PHP 4.x does not have a built-in SOAP library, you can use a 3rd party library. This example uses NuSOAP, however other libraries like PEAR::SOAP may work as well. NuSOAP is a PHP-based (i.e. no extensions to install) SOAP/Webservices library. It is available for download from here
HTTPS POST method
If you do not want to use the SOAP Webservices provided, you can instead, use the HTTPS POST method. This acts in a similar way to POST'ing a form from a web page, except that the result of the POST is read back into a variable, at which point it can be parsed for the relevant return information. Details on the return fields can be found in the Developer Documentation.
Download: PHP Example code bundle (.zip)
Note: As the SecurePayTech.com services (both SOAP and HTTPS POST) are accessed via SSL, you need to have the cURL extension installed, with SSL enabled, on your webhosting server in order to use PHP with the SecurePayTech.com payment processing services.