FusionPBX has a click-to-call application that it is not very easy to find, but it is not hidden at all. The click-to-call capability allows the linking between to endpoints from a http event. To be more clear, a perfect click-to-call example is the one that bank pages have on their pages, where you put your phone number, click the button and after a moment you get a call from the bank.
Twilio is one complete VoIP carriers these days. Among its SMS capabilities, it provides sip trunks as well. The good or bad thing about Twilio is that its SIP trunk only works with SSL/TLS. This will help you to warrant your confidentiality but it needs more work from you to make it work. I will talk how I did it.
Today, I am publishing the RPMs for SNGrep 1.4.4 All you need to do is to add my OKay's RPM repository, and just install it. SNGrep is a tool for displaying SIP calls message flows from the terminal. It supports live capture to display real-time SIP packets and can also be used as PCAP viewer.
If you wonder what is the big difference from my RPM's, these have all the options enabled as much as possible. This RPM enables the HEP/EEP protocol, very handy if you want to use it to interact with Homer.
RPM's are available for Centos 6 and 7. And you can find it if you type yum search sngrep.