In truth, there’s just no need to sustain the account. Anyone who needs a free SIP account can get them from other sources like OnSIP, IdeaSIP and Gizmo5. Once you have a SIP account the entire realm SIP URIs is available to you, including me.
I can’t help but have fond memories of using Free World Dialup in my earliest experiments with VoIP, SIP, et al. I’m grateful that Pulver & Company offered the service.