**Magento 1.7 does not support PHP 5.6**

It says so on [the official system requirements page][1]

[![enter image description here][2]][2]

You can expect a [Blank screen][3] when you upgrade.

I advise you to test PHP 5.6 on a stage site first before going live.


  [1]: http://devdocs.magento.com/guides/m1x/system-requirements.html
  [2]: https://i.sstatic.net/mqN4o.png
  [3]: https://magento.stackexchange.com/questions/60415/magento-1-7-0-2-on-php-5-6-is-not-loading