Memorandum for US Owners and Operators Using GPS to Obtain UTC Time

listening to the national institute of standards and tech. radio station WWV broadcasts one can see a cell phone may be off by large fractions of a second.
if you’re interested the Time/standard time interval is broadcast continuously and the minit is stated every minit on 2.5, 5, 10, 15 and 20 MHZ.

And if it’s a man’s voice you’re hearing WWV in Fort Collins, Colorado. If it’s a woman’s voice it’s WWVH in Hawaii.

But then there’s this: Shutting down WWV, WWVH and WWVB

just for your info its only in seconds but GPS time is not UTC time at the moment.
If it matters make sure you know which one you are using