Four ways to get a second phone number, compared

The four options, in one breath

You can get a second phone number by adding a second SIM or eSIM to your handset, by installing a calling app, by signing up for a business phone system, or by taking a line that an AI assistant answers. Every one of them gives you a number to hand out that isn't your personal mobile.

Which is best? For a true second mobile number, the eSIM. For cheap and quick, the app. For a team, the phone system. And if the real trouble is calls going unanswered, or calls you never get round to making, the AI line. The question that sorts them is a simple one: what happens on each when you can't answer?

A second SIM or eSIM

This is a second mobile plan living in the same handset. Most recent phones take two lines at once, and the phone shows you which one a call came in on. It's a proper carrier number, so texts work fully, signal is as good as your first line, and the verification codes that some services refuse to send to app numbers will reach it.

The cost is a second plan every month. And when you can't answer, it behaves exactly like your first number: it rings out and goes to voicemail. You've doubled the numbers and doubled the voicemail boxes.

A calling app on your mobile

An app gives you a number that rings inside the app, over your data or wifi. You can be up and running in minutes, often for very little, sometimes for nothing if you'll put up with adverts. Most apps text in both directions and will email you a transcript of any voicemail.

The weak spots are practical ones. Call quality follows your data connection, so a poor signal means a poor call. Some banks and sign-up forms won't accept app numbers. And a free number can be taken back if you stop using it. When you can't answer? Voicemail again, though usually a tidier one.

A business phone system

This is the grown-up option for a team. One main number, extensions for each person, a greeting, opening hours, ring the front desk first and the workshop second. It runs on apps and desk phones, and you pay per person per month.

When nobody answers, a phone system gives you choices: try someone else, play a menu, or send the caller to a shared voicemail box. That's a real improvement if there are people to try. If it's just you, the system will route the call very cleverly to the same person who couldn't pick up. It takes an afternoon or more to set up well, too.

A line an AI answers

This is the kind we make, so weigh our opinion accordingly. It's a real number in your area code, with its own email address, and an AI assistant answers it. When you can't pick up, the caller gets a conversation. The assistant finds out who's calling and what they need, and you get a written summary afterwards. It also makes calls for you. How it works has the steps.

Now the limits. It's the assistant's number, not a second handset for you: you talk to it, and it talks to everyone else. Texts to the line always arrive and are saved, but texts from the line to other people are limited for now, so anything that must arrive goes as a call or an email. Numbers are US only today. And call time is metered by the minute within a monthly plan, which you'll find on the pricing page.

What each one does when you can't answer

Here's the comparison squeezed down to that single moment.

• Second SIM or eSIM. Rings out, then voicemail. The caller leaves a message or doesn't.
• Calling app. Rings out, then voicemail, often with a transcript sent to you.
• Business phone system. Tries other people or plays a menu, then voicemail if nobody's free.
• AI-answered line. Answers, asks the questions, and sends you the details in writing.

You can combine them

These aren't rivals in every case. An AI line is an ordinary number from the outside, so a number that can forward its unanswered calls can forward them there. On a mobile plan that's a short code: *71 plus the number on Verizon, and *61*1 plus the number then # on AT&T and T-Mobile.

So one common arrangement is an eSIM for the business number you text and talk from, with its missed calls going to an assistant in place of voicemail. If privacy is what started you looking, we've a separate piece on keeping your mobile number private.

Which one for which situation

If you recognize yourself in one of these, that's probably your answer.

• You want work and personal kept apart, and you answer your phone. Second SIM or eSIM.
• You're selling something online or need a number for a few months. Calling app.
• You text customers all day. Second SIM, or an app that texts well.
• There are four of you and the phone should ring whoever's free. Business phone system.
• You work with your hands and calls pile up while you do. AI-answered line.
• You put off phoning the dentist, the garage and the insurer for weeks. AI-answered line, for the calls it makes.

Common questions

More on comparisons

• AI receptionist vs human receptionist: what each is actually better at
• AI answering vs voicemail: what your callers experience
• Virtual phone number vs AI phone number
• Unlimited vs per-minute AI phone plans: how to choose