I'm pretty certain that CDMA towers, at least, had exceptionally accurate clocks for something related to the technology (synchronizing the chip code maybe? it's a guess).
Not sure if this applies to GSM as well, but CDMA used to be an acceptable clock source for a Statum 0 clock source.
Not sure if this applies to GSM as well, but CDMA used to be an acceptable clock source for a Statum 0 clock source.