Second phone number for business: four ways to get one

The short answer

You can get a second phone number for business in four ways: put a second SIM in your phone, add an eSIM from a prepaid carrier, add a line to your existing carrier plan, or sign up for a business phone app that gives you a number over the internet. All four give you a separate number so customers stop calling your personal line.

The difference is who controls the number and who can answer it. A SIM, eSIM, or carrier add-on ties the number to one handset and one carrier account, usually a personal one. A business phone app ties the number to a business account, so several people can answer it and you can hand it to someone else when staff change.

If you work alone and will always be the one answering, a second SIM or eSIM is cheap and simple. If anyone else will ever answer, or you want to keep the number when an employee leaves, a business phone app is the only option of the four built for that. The rest of this post goes through each option and the trade-offs.

Option 1: A second SIM in a dual-SIM phone

Most phones sold in the last few years can hold two lines at once, either two physical SIMs or one physical SIM and one eSIM. You buy a second SIM from any carrier, put it in, and the phone rings for both numbers. You label each line in settings so you can see which one a call came in on.

The good parts: it costs whatever the cheapest plan is at the carrier you pick, it works without any app, and calls sound exactly like your personal line because they are carried the same way. You can also set which line a contact uses, so a saved customer always gets called from the business number.

The weak parts are the ones that matter as you grow. The number lives on one handset, so nobody else can answer it. Call history, voicemail, and texts from both lines sit in the same apps, so it is easy to text a customer from the wrong number. And if the phone is lost, or an employee holding it leaves, the number goes with the SIM and the carrier account it belongs to.

Option 2: An eSIM from a prepaid or online carrier

An eSIM is the same idea as a second SIM without the plastic. You sign up online, scan a code, and the second line appears on your phone in a few minutes. Many prepaid and low-cost carriers sell eSIM plans by the month with no contract, which makes this the fastest way to get a number today.

The trade-offs match the second SIM: one handset, one person, and the number stays with the account holder. There are two extra points to check. Some cheaper eSIM plans are meant for data or travel and limit calling and texting, so read the plan before you buy. And some carriers make it harder to port a number out of a prepaid plan, so ask how to get your account number and transfer PIN before you give the number to customers.

An eSIM makes sense for a solo operator who wants a business number this afternoon and does not plan to add staff soon. If you later outgrow it, you can port the number into a business phone service, as long as you kept the account details.

Option 3: A carrier add-on line

The third route is to call your current carrier and add a line to the plan you already have. Most carriers charge a fixed amount per extra line each month, and the line can go on a second device or, with a dual-SIM phone, on the same handset as your personal number. Some carriers also sell a 'second number' feature that adds a business number to your existing SIM through their own app.

This is convenient because it is one bill and one support line. The catch is ownership. The number belongs to whoever holds the carrier account. If that is your personal account, the business number is practically yours, not the company's. If you add a line to an employee's account to save money, the employee controls the number and can keep it when they leave.

Carrier rules on moving a number between accounts, or out to another provider, vary by carrier and plan. Rules change, so confirm them with your carrier directly. This is a general description, not legal advice.

Option 4: A business phone app

A business phone app gives you a number that lives on a service account rather than a SIM. Calls and texts come in over the internet to an app on your phone, your computer, or a desk phone. The number belongs to the business account, and the account admin decides who can answer it.

This solves the three problems the SIM-based options share. Privacy: the business number is in its own app with its own call log, voicemail, and text threads, so your personal line stays personal. Sharing: a shared business number can ring several people at once, and the first to answer takes the call. Staffing: when someone leaves, you remove their login and the number keeps working for everyone else.

Onyx Phone is one of these. Every user gets an included US local number, teams usually share one number, and calls ring the browser, the phone app on iPhone and Android, and SIP desk phones at the same time. Plans are per user, starting at $17 a month; full details are on the pricing page.

Two things to know before you commit. Business apps run over data or Wi-Fi, so call quality depends on your connection. And in the US, texting from a business number requires carrier registration (called A2P 10DLC) before messages will go through. Onyx Phone files the registration with you and approval usually takes one to two weeks. Carriers set these rules, they vary and change, and this is general guidance, not legal advice.

How the four compare on privacy, sharing, and keeping the number

Here is how the four options compare on the three things most owners ask about: who owns the number, how many people can answer it, and what happens when someone leaves.

On cost, work it out from your own headcount rather than from anyone's headline price. For SIM-based options, multiply the per-line monthly charge by the number of people who need the number, and add the cost of any second handsets. For a business phone app, multiply the per-user price by your headcount, then add any extra numbers you want.

With Onyx Phone that is $17 a user a month on Starter, with one number included per user and $5 a month for each extra number. Grasshopper, by comparison, charged $18 a month per account for its True Solo plan when we checked in October 2026. Pricing models differ, so compare them on your actual headcount, not on the lowest advertised figure.

• Second SIM: owned by the carrier account holder, usually you. One handset, one person. If the phone or the person goes, the number goes too unless you port it out first.
• eSIM: same ownership and same one-person limit as a second SIM. Fastest to set up. Check that the plan allows porting out before you rely on it.
• Carrier add-on: owned by whoever holds the carrier account. One device per line, so a second person needs a second line and a second monthly charge. Moving the number to the business later means a port, with the account holder's cooperation.
• Business phone app: owned by the business account. Any number of people can answer from phones, computers, or desk phones. Staff changes mean adding or removing a login; the number does not move.

If you already gave customers your personal number

Most owners come to this question after the fact: the personal cell is already on the truck, the invoices, and a hundred customers' phones. You have two choices. Move the personal number to the business and get a new personal one, or get a new business number and move customers to it over a few months.

Moving the personal number to the business is cleaner for customers because nothing changes for them. It means porting the number to a business phone service and getting a new personal SIM. Porting into Onyx Phone is free and usually takes 3 to 7 business days; the porting guides list what each carrier asks for. The downside is that friends and family will call the business line for a while.

If you get a new number instead, tell customers in writing and give them a date. Here is a text you can copy, followed by the other places to update in the same week.

• Text template: Hi [first name], it's [your name] from [business]. We've set up a dedicated business line: [new number]. Please save it; it's the best way to reach us for scheduling and questions. My personal cell will stop taking work calls on [date]. Thanks!
• Update the number on your website, invoices, estimates, email signature, Google Business Profile, vehicle lettering, and any directory listings.
• Keep the old personal number active but let work calls go to voicemail with a greeting that reads out the new number. After two or three months, most callers will have switched.

How to decide

Answer four questions and the choice is usually clear.

Whatever you pick, write down the account number, the transfer PIN, and who the account holder is, and store it where the business can find it. That one step is what makes the number portable later, and it is the step most people skip.

• Will anyone other than you ever answer this number? If yes, choose a business phone app. SIM-based options cannot ring two people.
• Do you want the number to survive staff changes, lost phones, and your own upgrade to a new handset? If yes, the number should sit on a business account, not a personal carrier account.
• Do you need to text customers from the number? Either route can text, but a business app will require US carrier registration first, so start that early.
• Do you need it today and you work alone? An eSIM gets you a working number in minutes, and you can port it to a business service later if you keep the account details.

Questions