NIST still maintains their Telephone Time-of-Day Service at (303)499-7111 and their Hawaii service at (808)335-4363 . Both my computer and phone were accurate to within 1 second on their default settings.
They also play a 440Hz signal 23 times a day so it’s useful for instrument tuning but to get the best signal you need a non-VOIP POTS line.
What happened to my signature line?