# Know what a number is. Before you send to it.

One POST, one answer, no resource to create or poll. The base lookup returns the number's country, the network serving it today, the network that issued its range, a flag saying whether it has moved between the two, and what kind of line it is. Five further properties are yours by naming them.

## Two networks, and the gap between them.

## That gap is what porting looks like in a response.

Phone number lookup is one of the two operations in the Bird Lookup API. Send a number in international format, with or without the leading plus, and you get back country_code, a network_info block for the carrier serving the number today, and an original_network_info block for the carrier that was allocated its range. When those two disagree the number has been ported, and flags says so. National-only numbers are rejected rather than guessed at, so a bad input fails loudly instead of returning a plausible answer about the wrong country.

## What comes back, and when.

The first three arrive with every lookup. The rest arrive when you name them in type.

## Every property tells you whether it answered.

Each block carries its own status: ok, unavailable, or inconclusive. Only ok carries a value, so you never have to inspect a response to work out that it is empty, and a field with no value is left out rather than set to null. The billing follows the same line. The base lookup bills once, a property bills only when its status is ok, and a lookup that fails bills nothing.

## One number per request.

There is no batch form, by design: a lookup is a live query against carrier data, and a batch would hide which of a thousand rows was answered and which was not. The rate limit starts at 10 requests a minute per acting credential and Lookup has its own budget, so screening numbers never eats into your sending. Send an Idempotency-Key and a retry replays the answer you already paid for instead of buying a second one.

## Go deeper in the docs.

Look up a phone number walks the request and every field it can return. The Lookup overview covers both operations and the property statuses in one page, rate limits documents the lookup group, and idempotency explains what a replayed answer costs.

## Run your first lookup on a number you know.

The dashboard runs the same operation one number at a time, which is the fastest way to see an answer before you write any code.