Both the original and the V revisions can be unlocked satisfactorily but they are not considered reliable pieces of hardware. Both versions can be prone to overheating (note the "can" and not "are") and, due to the plentiful availability of the B revisions, should be avoided.
That said, over a year ago now, Bald_Eagle1 sent to me an original type (not V nor B) HG612 modem (with the earlier SP06 firmware). It was promptly upgraded to the unlocked variant of the SP10 firmware and was used in a number of my experiments without any trouble or signs of overheating. With BE1's agreement, that modem has now been passed on to Walter as stock for his legendary "wheelbarrow" which is used in resolving Internet service problems in Ewhurst and the surrounding Surrey districts.
