We recommend CounterPath's X-Lite softphone.  
However, you will need to contact them directly as they are a 3rd party supplier and we can only offer limited support with this software.

You can download the X-Lite softphone for FREE at the following links, choose the one relevant for your computer i.e. PC or Mac versions.

Please be sure to use the links we suggest here rather than others you may see elsewhere as there a different versions of softphones and you need the VoIP versions for them to work with our system.

Windows PC link only:   https://www.counterpath.com/x-lite-download/

Mac link only: http://www.counterpath.com/x-lite-for-mac-download

Help desk UK number: +44 (0) 20 3327 2020

XLite: http://www.counterpath.com/store-faq/ or visit: https://support.counterpath.com/hc/en-us

Please note: we do not recommend the use of any other softphone software, of which there are lots out there as we cannot be responsible for the quality and security of using other softphone providers.