The person who texted you that 11pm message about the sofa you sold in March has saved your number, as have the four who came before. A single ad can give your personal number to a dozen strangers, and none of them will be bothered to delete it.
What a stranger does with your number
A WhatsApp account, a ticket, of sorts, exists only for a user with a corresponding phone number, which you certainly have. Whoever saved your number in their contacts or saved your contact to WhatsApp as a dedicated profile can call or receive you, at will. Changing the number on the account carries everything with it, but does nothing to reach into other people's phones.
And keeping that profile visible to 'my contacts', rather than 'everyone', can cut down what they see about you. From Settings, Privacy, About or Profile photo can be adjusted to restrict to 'My contacts'. Every list of contacts, a person with your number has, could include a huge number of strangers. According to Ofcom, in October 2021, 82% of UK adults, nearly 45 million people, had been targeted by scam calls or scam texts in the three months prior. The Telephone Preference Service is the UK's official register for opting out of unwanted live cold calls. It has no provision for people who simply keep your number.
The sofa went at 21:47
Three-seater in oatmeal velvet, £140, on Facebook Marketplace, from a flat off Kirkstall Road, Leeds. At 21:47, a message from a man called Danny: cash, he could come tonight. The number she used to give out for selling had been the virtual number for WhatsApp, and its profile had no photo.
He rang her at 22:05, but she let it ring for the time it took Silence unknown callers to kick in, 20 seconds, which it did without a sound. She rang back, and he was on Burley Road, outside a Co-op, 20 mins away, with 120 in his pocket. She took it. It had been off until a friend helped her switch it on. The TPS register does nothing for a man like Danny, who just kept her number. A second WhatsApp number online costs from $0.99 per month at MoreMins.
Questions sellers ask
How do I tell buyers which phone number to use for enquiries?
Facebook Marketplace and Vinted keep buyer messages inside the app, so you don't need a separate line there. Make sure you are not hiding the published line in your ad text; that is where you put your "other" number. If you do have a separate line, put the number in ad copy (full phone number, country code) everywhere you publish it, profile bios and autoforwarders. You can keep WhatsApp running on your real number, but all that will mean is that a dozen unfamiliar faces are holding your number in their phones, and a bunch of unfamiliar groups are chatting.
Can I just use WhatsApp Business on my normal number?
The business app can run on a second device and second number.
Will buyers notice they are messaging a different number?
As long as it is reachable and you are responsive. Include the full country code, so it is tappable. The cheapest US or UK number is $0.99 a month, and incoming texts are free.
What happens to the old number after I stop using it?
It stays in everyone's phone. Moving a WhatsApp account to a new number carries over messages and groups, but not contacts. Those keep the disposable number, which is why that line should be published in ad copy as well as in bios and autoforwarders.