Panacea Mobile offers HTTP, SMPP and SMTP API connectivity. They, too, have global coverage and offer the cheapest rates with such an advanced API. Have a look at this PHP script featured here: bakery.cakephp.org/articles/view/component-to-send-sms-text-messages
You can also view the Panacea Mobile API Guide on the support site - look under the API guides.
You can view their pricing by volume and country on the sms gateway page.
