It sounds like one of the cells in the battery is dying, which generally causes the battery to go from showing a full charge straight to being almost empty when the unit starts to draw on that cell. I had that problem with a Dell computer throughout the time I owned it.

But I dont know what the :no connection to base" or "Line busy" has to do with the cells, unless it just means that the phone wont perform pretty much at all when under the load of actually working!

In my case, even with a battery which has been charging for 24 hours, it wont register/link to its base.

Unless there is such a thing as a surface charge which makes the charge indicator light up but which wont let the phone work UNDER LOAD at all?