A busy sign that follows your calendar: stand the Duo as a tent to face the room
Does Callsign work on iPhone Duo?
Yes, from launch day, says its App Store page: stood as a tent the sign faces the room on the cover, and folded like a laptop it sits on the top half with call controls below.
- App Store confirmedMoosa, the developer, in a submission to FoldHunt on October 24, 2026. The App Store seller is Moosa BV. Callsign came out on October 23, 2026, and its App Store description has a section on iPhone Duo. The website says it was designed for iPhone Duo; it has no captures of the app running.
Adapted for the fold
- Standing · Hands-free
The sign faces the room
Stand the Duo on your desk as a tent and the cover shows the room whether you're free or busy, driven by your calendar.
- Book · Partly folded
Sign up top, controls below
Folded to 90° like a laptop, the sign stands on the top half, with the time left and your call controls on the half lying flat.
- Open · Inner display
Gallery and editor
Open, the inner display holds the sign gallery and editor; half open like a book, the gallery and the sign controls sit side by side.
About Callsign
Callsign is a busy sign for working from home, by Moosa. It reads your calendar: when a meeting starts the sign goes up, and when it ends it says you’re free, with nothing to press. On other iPhones it works in StandBy.
It was designed for iPhone Duo. Stand the phone as a tent and the sign faces the room on the cover; fold it to 90° like a laptop and the sign stands on the top half, with the time left and the call controls below. Open, the inner display holds the sign gallery and editor. Split View is coming, the developer says.
Evidence reviews
What we checked, when, and what the evidence establishes. Each record preserves the support label at that check.
· App Store page reviewed
App Store confirmed · iphone-duo
The App Store description mentions iPhone Duo: "MADE FOR IPHONE DUO Fold your Duo into a tent and the sign faces the room on the outer display." (version 1.0, released October 23, 2026).
App version: 1.0.
Store text only: we haven't seen the app running, and the store page doesn't show how each pose is used.
View reviewed evidence ↗
Related guides
iPhone Duo poses: closed, open, book, standing and Split View
A plain-language guide to the ways you will hold iPhone Duo, what the phone itself does in each, and the apps and ideas that make the most of them. For anyone buying one, and for anyone building for it.
The best iPhone Duo apps so far (October 2026)
The apps worth installing now that iPhone Duo is on sale, from the apps Apple named as launch partners to indie apps whose developers have shown a real iPhone Duo layout, picked for what they do when you open the phone.
Do your apps work on iPhone Duo? What happens before they're updated
Every iPhone app opens on iPhone Duo, but only updated ones fill the inner display. What an app looks like before its developer adapts it, how to tell which are ready, and which popular apps have said so.
Is this your app?
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<a href="https://foldhunt.com/apps/callsign/"><img src="https://foldhunt.com/badges/featured-on-foldhunt.svg" alt="Featured on FoldHunt" width="220" height="54"></a>Need to update the listing? Email the editor.
Sources: Callsign on the App Store (apps.apple.com) · Callsign website (getcallsign.app)
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