Short answer: Put a second phone number between you and every stranger who messages your listing. Use a second phone number app to get a number for calls and texts, post that number in your Marketplace, Craigslist, and OfferUp listings instead of your real one, and route all buyer contact through it. When the sale closes, you keep the number for the next listing — and your personal line stays out of the resale loop.
Here is the problem nobody warns you about when you sell your first couch online. The buyer texts. You reply from your real number. The sale falls through — but now your number is in their phone, maybe in a screenshot, maybe pasted into a "verify your identity" message a few days later. The U.S. Federal Trade Commission's consumer advice on online-selling scams describes exactly this pattern: scammers harvest seller phone numbers from public listings and use them to send verification-code phishing texts and fake "is this still available" bait. Your number was the leak.
Why a separate number actually reduces spam (the reasoning, not a promise)
The privacy payoff is structural, not magical. A second phone number app gives you a real number that rings and texts on the same phone, but lives apart from your carrier line. So when you post it, three things change:
- Your real number is never published. The listing exposes the disposable line instead, so scrapers and resale-spam lists collect that one — not your personal cell.
- Spam stays quarantined. Texts to the second number arrive in the app, not your default Messages inbox, so a flood of "still available?" bots does not bury texts from your dentist or your kid's school.
- You can cut it off. If one number gets buried in spam after a high-traffic listing, you retire it and provision a new one. Your contacts, banking, and two-factor logins never move.
That last point is the difference between "disposable" and "reusable." You do not need a fresh number per listing. One number can serve months of sales, and you only burn it if a specific listing attracts so much junk that triage stops being worth it. Reuse by default; replace by exception.
Claim: Posting a second number instead of your carrier number reduces spam to your real line.
Evidence: The FTC consumer advice on online-selling scams documents that phone numbers exposed in public listings are a common vector for verification-code phishing and bait texts.
Limit: This does not stop spam entirely — it relocates it to a number you control and can replace. It does not block a determined scammer who already has your real number from elsewhere.
Action: Keep the carrier number off every listing and route buyers to the second number only.
The setup: one reusable number, ten minutes
I am not going to claim a stopwatch figure here — your time depends on your phone, your app store, and whether a number plan needs purchase. The Text Call app setup and FAQ walk through provisioning; treat the steps below as the reproducible sequence, not a timed benchmark.
- Install a second phone number app and provision one number. Pick an area code you are comfortable showing buyers — local codes get fewer "out of town scammer" assumptions on Craigslist.
- Label it in your own contacts. Save it as "SELLING LINE" so you instantly know which inbox a message lands in.
- Decide on notifications. Turn on alerts for the selling line during an active listing; mute it once the item sells so the slow trickle of late spam does not nag you.
- Confirm what the app supports before you rely on it. Some platforms restrict whether VoIP numbers can receive certain verification texts. Whether a given service accepts your second number for sign-up codes changes over time, so check the Text Call app FAQ and test it once with a throwaway login rather than assuming.
That is the whole foundation. Now the part that does the real work: the listing copy.
Copy-paste listing language that routes buyers to the second number
The trick is to make the second number the obvious and only contact path, so buyers never think to ask for your "real" one. Drop these into the description field. Adjust the number format to your country.
Neutral, for any platform:
Serious buyers: text (555) 010-0123 with the item name and your pickup window. I respond to texts faster than app messages. Cash or in-app payment only.
Facebook Marketplace keeps messaging inside Messenger by design, and Facebook's own Marketplace safety guidelines recommend keeping conversation on-platform until you trust the buyer. So lead with Messenger and offer the number only after a real reply:
Message me here first. Once we set a time, I'll share a text number for pickup coordination.
Craigslist already proxies your email through an anonymized relay; do the same for your phone by posting only the second number. Craigslist's safety guidelines push hard toward local, in-person, cash deals — your copy should echo that:
Local pickup only. Text (555) 010-0123 to arrange. I will not ship, and I will not take Zelle/gift-card "overpayment." Cash at handoff.
That last line matters. The FTC consumer advice repeatedly flags overpayment and gift-card requests as classic resale-scam tells. Putting the boundary in the listing filters out a chunk of bad actors before they ever text.
A method to actually see the spam difference (run it yourself)
I will not hand you a fabricated "we cut spam 80%" number, because I have not run that test on your phone and your listings. Instead, here is a method you can run to measure it for your own situation:
- For your next two listings of similar items, post the second number in both.
- Each evening during the listing, tally texts to the selling line in two columns: real buyer vs spam/bait (gift-card asks, "is this available" with no item name, verification-code requests).
- Keep a parallel count of any junk that reached your real number over the same week.
- After the items sell, compare. The signal you are looking for is simple: did your carrier line stay quiet while the selling line absorbed the noise?
Treat the result as directional for your habits, not a universal stat. The point of the method is that the privacy benefit is observable — you can watch the spam pool collect on the number you can throw away.
One honest caveat about proof of sale
A second number protects your contact info, not your paper trail. For higher-value items, keep your own record of the handoff: a photo of the item with the buyer's agreed price, or a scanned receipt if you wrote one. A quick capture with a scanner app like Scan Cam turns a handwritten "paid in full, as-is" note into a clean PDF you can keep — useful if a buyer later disputes the condition. The number keeps strangers off your personal line; the receipt keeps the sale itself clean.
FAQ
Can I use one second number for all my listings, or do I need a new one each time?
One reusable number is the practical default. You only retire a number when a single high-traffic listing buries it in spam past the point of useful triage. Because the second phone number app keeps your real line separate, replacing the selling number never touches your contacts, banking, or two-factor logins.
Will buyers trust a number that isn't my "real" one?
They cannot tell the difference — it rings and texts like any number. To build trust on Facebook Marketplace, follow Facebook's guidance and keep early conversation in Messenger, then share the text number once you've set a pickup time. On Craigslist, a local area code reads as more legitimate than an out-of-area one.
Can the second number receive verification codes for marketplace sign-ups?
Sometimes, but not always — some platforms restrict verification texts to certain number types, and this changes over time. Do not assume. Check the Text Call app FAQ for current support and run one test login with a non-critical account before you depend on it. If a code does not arrive, use your real number only for that one sign-up and keep the second number for buyer contact.
Does a second number stop scams completely?
No. It relocates spam to a line you control and can replace, and it keeps your real number off public listings — which the FTC consumer advice identifies as a key exposure point. It does not stop a scammer who already has your real number, and it does not replace basic caution: meet in public, take cash or in-app payment, and refuse overpayment or gift-card schemes.
What if a buyer insists on calling instead of texting?
Let them call the second number. A second phone number app handles calls and texts on the same line, so you can take the call without exposing your carrier number. If the call feels off, you simply do not pick up next time — and after the sale, you mute or retire the number.
What I'd do first
Before your next listing goes up, provision one reusable second number, label it "SELLING LINE," and paste a routing line into the description that points buyers there. Keep your carrier number off the post entirely. Run the spam tally on your first two listings so you can see the quarantine working with your own eyes. Text Call is built by CodeBaker, which makes phone-first utilities for exactly these "I need a number I can hand to a stranger" moments. The decision is binary: either your real number is in the listing, or it isn't. Make sure it isn't.