Major update
Version 2.0 of our Smartmessages.net PHP API client library is much improved. It's now based on the popular Guzzle HTTP library. As a result, it now requires a minimum of PHP version 5.4, though we recommend you use the latest 5.6. If you need to run on 5.3 or lower, use the previous release.
This release also adds support for the new addSubscription API call.