What is the collective for phone?

There isn't a widely accepted or commonly used collective noun for phones.

Here are a few options, depending on the context:

Informal:

* A pile of phones

* A stack of phones

* A bunch of phones

Slightly more formal:

* A set of phones

* A collection of phones

Specific:

* A fleet of phones (for a company)

* A bank of phones (for a call center)

Ultimately, the best collective noun depends on what you want to emphasize.