Definition
In Korea, the ansim beonho ("safe number") service is a privacy tool that gives you a temporary virtual number starting with 050, instead of your real mobile number, whenever you must leave contact details for a stranger, such as on a delivery box, in a secondhand sale, or on a parking notice. Calls and texts to that number pass through a relay system and reach your real phone safely.
Why does a delivery box show a different number?
Look at a box from an online order. In the spot for your mobile number, you will often see an unfamiliar number starting with 050. This number acts as a kind of digital mask that keeps your personal information from leaking out.
Delivery boxes sit in hallways outside your door or get dumped in the apartment recycling area, where many strangers can see them. If your real number, starting with 010, were printed there, you could become a target for spam calls, voice phishing, stalking, and other dangerous crimes.
With a safe number, when the delivery driver calls the 050 number on the label, the phone network picks up the call in the middle and connects it to your smartphone. The caller talks to you without ever knowing your real number, and your number stays hidden from them too.
To be a bit more precise: mapping and expiration
To be a bit more precise, the heart of the safe number is a virtual number mapping table that the carrier's switching server manages in real time. Mapping means keeping a digital ledger that pairs a temporary virtual number with the user's real phone number.
When you pay for an order at a shop, the system picks one unused 050 number and ties it to your number, one to one. Later, when the driver calls that number, the relay server checks the ledger and, in a split second, reroutes the call to your real smartphone.
This pairing is not permanent. A few days after delivery, or once the deal is done, the system wipes the link from the ledger. If someone calls an expired safe number, the connection is cut off right away. That greatly lowers the worry about your privacy being invaded after the transaction ends.
Texts work, so why not identity verification?
Early safe numbers could only receive calls. As the technology improved, they now support two-way calls and text message relay. If a driver texts you from the 050 number, saying the package is at your door, it reaches your smartphone. Depending on the number range or service, though, picture messages (MMS) may not be passed along.
You cannot use a safe number for the identity checks needed to sign up on a website or use mobile banking. A safe number does not prove who you are or whose name the line is under. It is only a temporary channel for passing messages along.
Also, phone resources are limited. Once a virtual number expires, it is taken back and given to another customer's new order. So if you save a safe number in your contacts to reach someone later, a few days on it may ring a complete stranger. Be careful.
Common misconceptions
When you call through a safe number, the phone company listens to or records the conversation.
The safe number server only guides the route that connects a call. It does not listen to or record what is said. Under Korea's Protection of Communications Secrets Act, carriers also cannot listen in on calls freely.
Once you get a safe number, you can keep it for life as your own second number.
Safe numbers for deliveries are usually temporary and last only a few days to a few weeks. When the period ends, the number is taken back and given to someone else's order. Some services, like parking notices, last longer, but even those connect only within the period and conditions the service sets.
Where you meet it
When you talk to a rider in a delivery app, you reach each other through a 050 safe number instead of your own number.
A 050 number is printed on the delivery label instead of your real number, so a discarded box does not leak your information.
When you park, you leave a 050 safe number on the windshield instead of your real number.
In one sentence
A safe number connects a temporary 050 virtual number in place of your real phone number, protecting your privacy and personal information.