How it happens
Nobody decides to use their personal mobile as their business line. The first customer asks for your number, you give them the one you have, and eleven years later it is painted on the side of a van, printed on four thousand invoices, listed in half a dozen directories, and saved in the phones of everyone you have ever worked for.
By that point it is not a phone number. It is infrastructure, and it belongs to the business rather than to you, whatever the account says.
What it actually costs
- You are never off. There is no version of your phone that is not the business phone, so the only way to stop working is to ignore calls that might be work.
- Your number is permanently public. It is on listings, on marketplace ads, on old job sheets, and it never comes back.
- You cannot hand any of it over. Taking on staff, a partner, or an office person means either giving them your phone or rebuilding the entire contact history of the business.
- Selling the business gets awkward. A trade business whose enquiries all flow to the founder’s personal mobile is worth less than one with a number that transfers, because the goodwill is attached to a handset.
- There is no separation of records. Which of those calls were work? For tax, for disputes, for anything — it is one undifferentiated log.
The cost is not the calls. It is that the asset your marketing has been building for a decade is attached to your personal life and cannot be moved.
The counter-argument, which is real
A personal mobile has genuine advantages and people who dismiss them have usually never run a one-person trade business. Customers reach you directly. There is no switchboard, no extension, no sense of being handled. For a sole trader that directness is much of what people are buying, and a second number can dilute it if it is handled badly.
It is also free, already in your pocket, and requires no decisions. That is not nothing when you are starting out and every hour matters.
When to change it
The honest answer is earlier than most people do, and the trigger is not volume — it is permanence. The moment your number is going onto something you cannot easily change, it should be a business number. Signage, a vehicle wrap, printed materials, a Google Business Profile, a website.
If that moment has already passed, changing later is still worth doing, but do it by addition rather than replacement.
Changing without losing anyone
- Get the new number and start using it everywhere new. Signage, listings, quotes, email signature, website.
- Do not turn the old one off. It will keep receiving calls for years, and every one of those is a customer.
- Forward the old number to the new one so nothing is lost while the change works through.
- Update your Google Business Profile and any directory listings, since those are where most new callers get the number from.
- Give it two to three years before you consider retiring the old number, and check the call volume on it before you do.
Where a text-back fits
Whichever number you use, the problem this page is really about is that you cannot always answer it. A separate business number does not fix that — it just means the calls you cannot take are arriving on a different handset.
What it does do is make the automatic reply cleaner: the message goes out under the business name, and the thread stays with the business rather than mixed into your personal messages. If you are setting up a business number anyway, it is the natural time to sort out what happens when it rings and you are on a job.
Written by the team at Kryon. We sell a missed-call text-back service, which is a conflict of interest worth stating outright — so where a guide would be improved by telling you not to buy anything, it does.