FA-96824 / Phone number formatting / Member archive

Caller ID display and callback string: unavailable numbers are shown as private · case 04

An unavailable caller is labeled "Private".

Member previewVariant 4 · 3 implementations · 11 checks per implementation

Case contract

Home country: trunk 0, code 42, exit 00, default area 55. Restricted -> ["Private", None]; unavailable -> ["Unavailable", None]; no digits -> ["Unknown", None]. For type "unknown": a stripped leading "+" means international, else a leading exit prefix is removed and means international, else a leading trunk is removed and means national, else subscriber. International: display "+digits"; callback is trunk + national part for the home code, otherwise exit + digits. National: trunk + digits for both. Subscriber: display digits, callback trunk + area + digits. Return [display, callback].

Why this case matters

Caller ID is shown on handsets and used for one-touch callback; a wrong classification displays a foreign number as local and calls back the wrong party.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
unavailable presentation	`["Private", null]`	`["Unavailable", null]`	Failed

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