For the last few months we've had a SIP / VOIP setup in our offices.
My experiments with accessing the system using a SIP client on my iPhone were disastrous.
However I hadn't had any reason to do any proper experiments with using a SIP client on my desktop until today.
I'm currently using "Telephone", which is functional, but not exactly amazing.
So what SIP client software would people recommend for use on Mac OSX?