What a phone takes
A telephone on a table does more than interrupt. It divides attention at the exact moment attention is the gift: a person mid-sentence watching someone else read a screen learns that what they were saying was worth less than a notification. Nothing has been said aloud, and the room has been told.
It also changes the shape of the evening. A screen left face up tells everyone present that the meal may be interrupted, and once one guest accepts an interruption, others begin to permit themselves one. The practice spreads faster than any rule could.
The rule a guest keeps
Before sitting: silent, and put away rather than set down. Not face down on the cloth, which is a compromise that keeps the possibility open, but in a bag or a pocket, out of the room’s sight. If a call is genuinely expected, say so on arrival, once, and name the hour it may come.
At the table: no reading, no replying, no glancing. If the call comes, excuse yourself to the host quietly and leave the room; return without explaining. Twenty seconds at the door is a courtesy, and a conversation at the table is a decision taken about everybody present.
The exceptions that are real
There are real ones. A parent with a child at home, a doctor on call, a house in difficulty, a family waiting on news. These are stated in advance, in one sentence, and then honoured with the smallest possible interruption. The exception is the reason for taking the call, not a licence for the evening.
What is not an exception is work that could have waited, a photograph of the table, a message to someone who is not present, or the small habit of checking. A guest who looks every eleven minutes is not doing anything urgent; they are somewhere else, and the room can tell.
What a host may ask
A host may set the house’s practice before the evening, plainly and once: telephones stay in the hall tonight. Said in the invitation or at the door, it is a house rule rather than a reprimand, and guests keep it readily. Said to one guest at the table, it is a correction, and a correction in public is what this institute exists to avoid.
Where a host says nothing, the guest follows the strictest reading in the room. If the host takes a call, that is permission for nobody. If the dinner is a working one where screens are expected, the host will say so, and a guest who watches the first five minutes will see it.
After the table
The meal ends before the telephone comes out. Calls are made in the hall, messages answered after the door has closed behind the guest, and photographs taken only with the agreement of everyone in them. A room is not photographed in order to be described to people who were not invited into it.
The habit worth keeping is the one a house teaches its children: the person in front of you is the whole of the evening. Everything on the telephone will still be there at eleven, and it will be worth less than the hour it cost.