A wrong phone number means a courier cannot call when they cannot find the door. When a customer updates their phone number through Update contact details, Tacey checks it is a real, correctly formatted number for the right country before it reaches your order.

The customer ticks Change my phone number (the box reveals the field), picks a country from the country selector, and types their number. They can type it however they like: with or without spaces, dashes or the country code.

Tacey checks the number against real numbering rules for the selected country: the right length, a real area or mobile prefix, and so on. A number that could not exist in that country is refused with:

> That doesn't look like a valid phone number for the selected country. Please check and try again.

Nothing on the order changes until the number passes.

The number is saved in full international format, with the country code, no matter how the customer typed it. So `(415) 555-0100` with United States selected is saved as `+14155550100`. Your courier, your SMS tools and anyone reading the order see one consistent format.

With this setting on, the country selector starts on, and stays locked to, the country the order ships to. That stops a customer ending up with a number for the wrong country by mistake.

If the customer types a number that already includes a different country code, for example a Philippine number on an order shipping to the United States, it is refused with:

> That phone number doesn't match the country this order ships to. Enter a number for the shipping country shown above.

When to turn it off: if many of your customers ship gifts to other countries, or travel, and give their own home number. Turning it off lets the customer pick any country in the selector.

If Tacey cannot match the shipping country to a phone code (a rare case for a few territories), the selector opens to any country automatically rather than blocking the customer.

Some numbers, like certain shared or toll-free ranges, do not belong to one country. Those are never refused for a country mismatch, since there is no mismatch Tacey can prove.

If the customer ticks the phone box and leaves it empty, it is treated as a mistake, not a request to delete their number:

> Enter your new phone number, or leave the box unchecked to keep your current one.

Only if you turn on Let customers remove their email or phone entirely can a customer clear their number, and they see a confirmation step first.