A second line you keep vs a one-off code
Most people looking for a second phone number want something that lasts: a number on a seller profile, a work account, a dating app or a travel booking that keeps texting you for weeks. That calls for a number that stays yours, not a code you read once and forget.
A private rental is built for that. You choose the country and the length, the number is dedicated to you for the whole period, SMS is unlimited and the inbox is visible only in your account. Rentals start from $4.99, and they are non-VoIP lines, so strict services are more likely to accept them.
If all you need is one verification code, a rental is more than you need. A private per-code number from $0.50 gives you the code in a private inbox and is refunded automatically if nothing arrives. Pick the rental when the account matters and you will need the number again.
How to set up a second phone number without a second SIM
Open the Numbers page, pick a country and a rental length, and pay from your wallet. The price for each country and duration is shown before you rent. The number is live straight away, with nothing to install and no SIM tray involved.
Copy the number in full international format and use it wherever you want your second line: a sign-up form, a marketplace listing, a booking, a profile. When a text arrives, it appears in your private inbox on ASMS.ai, on any device you log in from.
Changed your mind? Cancel between 5 and 120 minutes after renting, before any SMS arrives, and you get a refund. After that the number stays yours until the rental ends.
Free second phone number: when it is enough
The free numbers on ASMS.ai cost nothing because they are shared. Anyone browsing the same number can read the same messages, and there is no account to create. The live pool is mostly UK numbers, plus the Netherlands, Finland and a few others.
That suits a one-off, low-stakes code: trying an app, a newsletter sign-up, a test form. It does not suit a second line, because you cannot keep the number to yourself, and popular apps often reject shared numbers or say the number is already in use.
Never use a free number for anything tied to money or account recovery. A code that resets a password or confirms a payment should only ever go to an inbox that you alone can read.
Second number app or a number in your browser
Second number apps usually ask you to install something, create an account and often subscribe before you get a line. ASMS.ai works in any browser on any device, and a rental is paid once for the period you choose, with no subscription to cancel.
The trade-off is that ASMS.ai is for receiving SMS. If you need to call people or text them back from the second number, you need a calling service as well. If you need a private number that receives verification codes, alerts and messages, a rental covers it without an app.
Developers can also manage numbers through the REST API and native MCP server, so a script or an AI agent can request a number and read incoming SMS without anyone using the site.
What people use a second line for
Work is the common case. A freelancer or small business can put a separate number on a work account or a supplier sign-up, so codes and alerts for the business land in one place and the personal number stays private.
Selling and dating come next. A number on a marketplace profile or a dating app keeps your personal mobile out of strangers' hands, and when the sale or the conversation ends, you let the rental lapse. Travellers use a second line too, so bookings and sign-ups have a number they can read while their home SIM is off.
Spam avoidance runs through all of these. Every form that gets your real number is another place it can leak or be sold. A second number takes that exposure instead. Use it for privacy, not for fake identities or getting around a service's rules.
If a service rejects your second number
Some services refuse VoIP numbers, and a few refuse anything that looks virtual. For a one-off code, follow a simple ladder: try VoIP High Quality (US +1) first because it is the cheapest, then the United Kingdom pool (+44 mobile), then a non-VoIP rental.
A per-code order that never receives a code is refunded automatically, so starting with the cheaper option costs nothing when it fails. The exact price and stock for each service are shown on the OTP page before you pay.
For an account you plan to keep, skip the ladder and rent. A rental is a non-VoIP line that stays yours, so the service can text you again for a new login or a security check while the rental runs.