"It is virtually impossible to deduce the original input from a hash if a strong hashing algorithm is used."

That's just not true when the "original input" is constrained enough, like, for example, a phone number.

It really makes no difference what algorithm you use - if it's fast enough for you to hash all the phone numbers in my contact list on my phone, I can have a set of rainbow tables for every possible phone number. There's just not enough entropy in 10 digit numbers for that to be an effective solution.