Will not run on OS X 10.12
Of all the SIP clients Ive used, this is about the best. I still feel its awefully expensive, but its one of the few that offered full Address Book compatibility, SIP TLS, and SRTP. The UI is a bit awkward. And under 10.11 it would crash when hanging up on a call. With 10.12, it will not run at all.
JoeRhodes10 about
Blink Pro, v4.4.6