What a phone line is not allowed to say.
A voice line that sounds right is easy to build. One you can leave alone with your callers starts with a list of what it must never do.
Making a phone line that sounds natural takes very little now. The voices are good and the delay is short enough for a real conversation. A model will also happily talk about anything, and that is the problem.
A line that answers your callers speaks for you. Everything it says, it says in your name, to someone who cannot see the screen behind it and has no reason to doubt it. So every line we build starts the way our other systems do: with the list of things it is not allowed to do.
It never confirms what the system has not done
The most damaging sentence a phone line can say is a confirmation that is not true. “Your booking is cancelled.” “Your account is unlocked.” Said with confidence and believed completely, it is wrong if the system behind the line refused the action or never received it.
The rule is mechanical. The line confirms an action only after the system that performs it has answered that it is done. If that answer does not come, the line says so, and a person takes it from there. A caller who hears “I could not complete that, a colleague will call you back” is mildly inconvenienced. A caller who hears a false confirmation finds out later, at the worst moment, and remembers who told them.
It knows who is calling before it acts
Some requests are harmless to answer for anyone, like opening hours or where to park. Others act on an account. For those, the line confirms who is calling before it does anything, and the way it confirms is decided with you, not improvised by the model.
It holds one language
Callers switch languages, and speech recognition that detects the language on its own can switch with them, sometimes in the middle of a sentence, sometimes when nobody switched at all. The line then answers in a voice that sounds foreign to the caller, which is enough to lose their trust.
So a line runs in the language it was set up for, and changes only when the caller asks for another one. It is less clever, and far more reliable.
It hands over instead of guessing
Anything the line is not set up to handle becomes a ticket or a transfer to a person, with what the caller said attached. A line that says “I will pass this to the team” for the right reasons is doing its job. A line that improvises an answer to sound helpful is not.
A test call is not always a test
On a line that can transfer calls, asking for a person makes a real phone ring somewhere. Tests belong on a separate number, with the transfers pointed at the people building the line. The number your callers use changes only after that.
Where to start
The list of what a line must never do is shorter than the list of what it can do, and it is the one worth writing first. If you would like to see it drafted for your own calls, tell us what your phone line handles today.