"Utilizing an advantage" is not idiomatic, and I have no idea what it would mean to "employ a phone number". That which is used, employed, or utilized should be a tool, implement, device, or instrument of some kind, something which can be wielded, literally or figuratively.
Let's use this key to see if it works.
We can use her to get to him.
We can make (good) use of Google mail because of its various features. We can put them to use. We can take advantage of those features. We can use Google Mail to good advantage.
But we cannot use, employ, or utilize advantages, not without sounding a little vacant:
We can use our advantage to our advantage.