I am running CiviCRM 4.7.6 on Drupal 7.43 on a CentOS 7 platform. I need to install CiviSMS with the Twilio and am running into a problem with the PHP version requirement of 5.5. CentOS natively has PHP 5.4.16. Can anyone advise on a better platform that gives me the ability to run CiviSMS?
Depending upon your hosting, you might be able to upgrade PHP on your CentOS server. A quick Google search showed some options, but I can't vouch for any particular guide.
I tend to work more on the Ubuntu/Debian side of things, and Ubuntu 14.04 LTS ships with PHP 5.5.9 out of the box. (And Ubuntu 16.04 gives you the option of PHP 5.6 or PHP 7.0, which isn't yet supported by CiviCRM.) If you aren't set in your ways, you might try switching over.
I don't think whatever PHP requirement you have is coming from CiviCRM or the Twilio extension. CiviCRM definitely doesn't require PHP 5.5 - and the Twilio code hasn't really changed for years, so I can't imagine that requires it either.
Please post a screenshot of the screen that says you need PHP 5.5 and maybe folks can help you more.