Sign In Get Started
Prepositions with nouns

“On call” vs “of call”

Use “on call” for someone available to work or respond when needed. “Of call” is not a standard fixed expression in modern English.

Quick answer

Which form is correct?

“On call” is the standard expression for being available for duty or emergencies. “Of call” is generally not used as a direct combination.

The doctor is on call tonight.
One engineer stays on call every weekend.
The sound of call bells echoed through the hall.

Choose the pattern by meaning

These forms are not interchangeable. Choose the construction by meaning, not by which preposition appears most often.

1
on call

Being available for work or emergencies

Use “on call” for people ready to respond when needed.

A nurse is always on call at night.
Our IT team remains on call during holidays.
2
on-call staff

Describing emergency availability

Use the hyphenated form before a noun.

The hospital hired more on-call staff this year.
3
call of duty

Using “of” in a different noun phrase

Here “of” belongs to another expression and does not compete with “on call.”

He answered the call of duty immediately.
4
call for + noun

Requesting or requiring something

Use “call for” when something is needed or requested.

This situation may call for action.

See the difference in context

The same subject can take different constructions because each sentence answers a different question.

Construction
Example
Meaning
on call
The surgeon is on call this weekend.
Available to work or respond if needed.
of call
The sound of call bells was constant.
Possible only when “of” belongs to another structure such as “sound of call bells,” not as the expression meaning available for duty.
on-call
We need more on-call technicians.
Adjective form used before a noun.
call for
The emergency called for immediate help.
A different expression meaning require or request.

Common mistakes

Some combinations appear in real text but do not mean what learners often assume.

Using “of call” to mean available for duty

English uses “on call” for emergency or standby availability.

✕ The dentist is of call tonight. ✓ The dentist is on call tonight.

Forgetting the hyphen before a noun

Use “on-call” before a noun but “on call” after a verb.

✕ She is an on call doctor. ✓ She is an on-call doctor.

Using “on call” as a verb

“On call” describes status, not the action of calling someone.

✕ I on call the manager. ✓ I called the manager.

Quick practice

Choose the expression that matches the intended meaning.

1. The technician is ___ call this evening.
2. The hospital needs more ___ staff.
3. The emergency ___ immediate action.

Check your sentence in context

Paste the complete sentence below. Linguix checks the preposition together with grammar, spelling, punctuation, and style.

Free to try · No signup required

Frequently asked questions

What does “on call” mean?

It means available and ready to work or respond if needed.

Is “of call” ever correct?

Not as a fixed expression meaning availability. It may appear inside larger phrases such as “sound of call bells.”

Why is “on-call doctor” hyphenated?

The hyphen is used because “on-call” functions as a compound adjective before the noun.

of, about, against, to or for racism? of, about, for, in or on friendship? of, about, for, on or to thing? of, about, for, to or with sex? of, about, on, to or for moon? "of access" or "with access"? "of accommodation" or "for accommodation"? "of accuracy" or "for accuracy"? "of action" or "in action"? "of actor", "with actor" or "by actor"? "of address" or "to address"? "of administration" or "in administration"?

Write with confidence in Linguix

Create a free account to check complete texts, apply suggestions, and save your documents.

Create a free account