Ok, I'm a little slow, but I think (hope, actually) I get it! I call the Grand Central number which calls the SIP number and the jablet serves it to my IT... Or something like that, no?

In any case, I've done this. I have used my cellphone and my called my GC # to call my tablet using the Gizmo client on the IT. What I haven't managed to do is to use the built-in internet calling app for the same purpose. It'd be nice to make use of that app instead of the, as the General said, rather 'bloaty' Gizmoware...pehaps I just need to try again?

There's a full guide for setting up your Gizmo account with the built-in SIP client here.

General, thanks very much! I'm sure I'd have encountered this with some more reading, but I much appreciate the direct link. I'm off home to tinker with it!

Cheers!