What's the word for "synonyms of a phrase"?

I believe "paraphrase" as a noun is the goose you're after.

The word is still synonym.

Following is Merriam-Webster's definition of the word. I am adding my own emphasis to expressions and phrase.

1 : one of two or more words or expressions of the same language that have the same or nearly the same meaning in some or all senses
2 a : a word or phrase that by association is held to embody something (such as a concept or quality)
       // a tyrant whose name has become a synonym for oppression

---

Note that the second and third example phrases in the question are not synonymous with the first (or even with each other).

The following are synonyms of call the police:

• contact the cops
• get in touch with the authorities

But these are not:

• report to the authorities
• report a crime

In the original phrase, nothing has actually been said about a report being made, nor about a crime having been committed. It describes a simple action, but makes no assumptions about why the action should be performed.