Classifieds and resale platforms treat a phone number as an identity. Some show it to buyers on the listing, some require one per seller account, and many only accept numbers from the country the marketplace serves. If you sell on one, your personal number ends up either public or permanently attached to a commercial identity.
This is for people selling under their own name who would rather not publish the number their bank texts. Ordinary sellers with an ordinary reason to keep two lines apart.
Where the friction actually is
Local-only acceptance is the common wall. A marketplace serving one country frequently rejects everything but its own dial code at signup, which stops anyone selling into that market from abroad before they start.
Personal and commercial identity get mixed. Once a number is attached to a seller profile it travels with disputes, payout checks and buyer contact for as long as the account exists, which is a poor fit for the number that also receives your bank codes.
Keeping it legitimate
Marketplaces separate browsing from selling for a reason: ratings, dispute history and payout identity are meant to follow a real person or business. Using a rented number to keep a selling account off your personal line is ordinary. Using one to spin up seller accounts after a suspension, or to run several accounts that pretend to be different people, is prohibited by our acceptable use policy and by the platforms themselves.
A rented number covers the verification step. It is not an ongoing line, so give the account an email and password you control for recovery.