Because it works almost flawlessly. In the last several months, I only had one instance where I had to log out of RingCX and log back in to make it work. With our Last VOIP, we had to do that several times per day. It is always easy to log calls, whether answering with the RingCX Salesforce dialer, desktop app, or mobile phone. Creating SOPs couldn't be any easier because RingCX just works!
We used to use SipVine before switching and they used an app called Bria for mobile stuff. It worked, but as we scaled as a business we needed more. That's where RingCX came in. Anytime a company makes a full-scale change it comes with pains, but to say that the pains for RingCX were minimal would still be an understatement. They helped us switch Seamlessly from our last VOIP; the whole process only took a few minutes, and then using the app, Salesforce integrations, etc., was incredibly easy.