GMT is not the preferred time standard now. GMT can be changed with
Daylight or Standard time change. I think most times are now considered
UTC which can be picked up on WWV. UTC does not change. You can get the
time with a phone call to 303-499-7111. Do not rely on a phone call during an
emergency and phones don't work. Also every 5 MHz on shortwave have WWV
and WWVH stations, one of which you should be able to hear.