Another word for untraceable

She was untraceable in the shadow world, until she emerged somewhere else.

Three calls were telephoned from Boston, New York and Connecticut while two were made on untraceable phones.

They're almost untraceable and have even showed up at our compound in Texas.

Now you've learned to use caution and untraceable phones, but I caught you're one mistake, didn't I?

Meanwhile, Wynn's level of Ancient magic made him almost untraceable.