How to set up call forwarding for your business line (every major carrier)

By the RetainCall Team · July 2026

Call forwarding is the single most under-used free feature on your phone. Almost every business line already supports it — you just never turned it on, or you turned on the wrong kind and it did something you didn't expect. This guide fixes that. By the time you're done reading, you'll know exactly which type of forwarding you want, the star codes to set it up on the major carriers, and how to test it in two minutes so you're not guessing.

No product pitch until the very end. This is a how-to, and it works whether you ever use anything we build or not.

First: the three kinds of forwarding (this is where people mess up)

"Call forwarding" isn't one thing. There are three completely different behaviors, and picking the wrong one is why people try it once, get a weird result, and give up.

1. Immediate (unconditional) forwarding. Every call goes straight to the other number. Your phone never rings. This is what you want when you're closing for vacation, or when you deliberately want a receptionist or answering point to take everything.
2. No-answer forwarding. Your phone rings first. If nobody picks up within a set number of rings, then it forwards. This is the one most owners actually want — you still get first crack at every call, but nothing dead-ends in voicemail.
3. Busy forwarding. Forwards only when your line is already in use — a second caller who'd otherwise get a busy signal or roll to voicemail gets sent onward instead. This is how you stop losing the second-and-third callers during a rush.

Most shops that miss revenue don't have an immediate-forwarding problem. They have a no-answer and busy problem: the phone rings out or the second line collides, and there's no backstop. So the setup you almost certainly want is no-answer forwarding, plus busy forwarding, both pointed at a person or service that will actually answer.

Rule of thumb: if you still want your own phone to ring first, you want no-answer forwarding — not immediate. Turning on immediate forwarding by mistake is the #1 reason people think forwarding "broke my phone."

Decide where the calls should go — before you touch a code

Forwarding is only as good as its destination. A no-answer forward pointed at a cell phone that's also unattended just moves the dead-end one hop down the road. Before you set anything, pick a real answer point:

• A second human — your spouse, an office person, a senior tech who's usually near a phone. Best if that person reliably answers and can at least take a name and callback number.
• A shared "front desk" cell that whoever's on rotation carries.
• An answering point that never misses — a human answering service, or an AI dispatcher. More on the honest trade-offs of those at the end.

Write the destination number down in full, with area code. You'll type it into the forwarding code exactly as you'd dial it.

The star codes, by carrier

Here's the part you came for. These are the codes you dial from the business phone itself (the line you're forwarding from), then press call. A couple of important notes first:

• Carriers change these, and some plans differ. Treat the table as your starting point and confirm with your carrier if a code doesn't take.
• The GSM-style codes (the ones that look like **61*number#) are dialed as one string and then you press call — you don't dial the number separately.
• The Verizon-style codes (like *71) are dialed, then you enter the 10-digit destination number, then press call.

A handy extra: on the GSM carriers (AT&T, T-Mobile, and most prepaid brands that ride their networks) you can set the ring delay before a no-answer forward triggers. Dial **61*number**SECONDS#, where SECONDS is 5, 10, 15, 20, 25, or 30. So **61*15551234567**20# forwards after roughly 20 seconds — about four rings — which is usually the sweet spot: long enough for you to grab it, short enough that the caller doesn't give up first.

To check what's currently set, GSM carriers accept interrogation codes like *#61# (no-answer status) and *#21# (immediate status). Useful when you can't remember whether you left a forward on.

If your business line is VoIP, landline, or a Google number

Plenty of shops don't run their main number off a cell carrier at all. The concept is identical; the setup lives in a web dashboard instead of a star code:

• VoIP systems (the phone service most modern offices use) almost always have "call forwarding" and "find me / follow me" settings in the admin portal. Look for a rule like "if unanswered after N seconds, ring [external number]." That's your no-answer forward.
• Traditional landlines from the local phone company usually support the same *72 / *73 immediate codes as Verizon, and often *90/*91 for busy and *92/*93 for no-answer. Your provider's support line will confirm.
• Google Voice and similar virtual numbers let you add multiple "linked" phones that all ring at once, and set which ones ring — that's effectively find-me forwarding from the settings screen.

Test it in two minutes (don't skip this)

Forwarding that you set but never tested is worse than none, because you'll assume you're covered. Run this test the moment you finish:

1. From a different phone, call your business line.
2. For a no-answer forward: let it ring and don't pick up. Confirm it rolls to your destination — not to your old voicemail.
3. Answer at the destination and make sure you can hear each other clearly.
4. For busy forwarding: get your business line on a call, then have someone else dial in and confirm they forward instead of hitting a busy tone.

If it rings out to voicemail instead of forwarding, the most common culprit is that your carrier voicemail is grabbing the call before the forward triggers. Fix it by shortening the forward's ring delay (the **SECONDS# trick above) so forwarding fires before voicemail does.

Why this one free setting moves real money

We've run the missed-call math in detail elsewhere, so here's the short version. The headline stat everyone repeats is that roughly 3 in 10 calls to service businesses go unanswered. The part that hides the damage is what happens next: most callers who hit voicemail never leave one — they just dial the next result. So the effective loss on a missed call is far higher than the miss rate itself.

That's from a setting that costs nothing and takes ten minutes. It won't catch everything — a forward is only as good as who's on the other end — but it turns "the phone rang out and the customer's gone" into "someone at least picked up." For a fuller breakdown of these numbers, see the real math on missed HVAC calls, and if you're a solo or one-truck owner deciding how much of the phone you should be answering at all, the one-truck owner's guide to not being the receptionist walks through the whole call-triage decision.

Where forwarding stops being enough

Honest limits, because forwarding isn't magic:

• The destination still has to answer. Forward a no-answer call to a cell that's also on a rooftop, and you've just moved the dead-end. Forwarding solves routing; it doesn't create a person.
• It doesn't handle two overlapping calls well. Busy forwarding helps, but if three come in at once you're back to the same collision.
• It doesn't book anything. The best case is a human who takes a message and a callback number — you still have to close the loop later.

For a lot of shops, that's fine — a forward to a reliable office person recovers most of the leak. But the calls forwarding can't save are the expensive ones: the 2am no-heat call, the Saturday-afternoon rush when everyone's already on a job, the week a cold snap 5×'s your volume. Those need an answer point that never misses and can actually take the booking.

That's the gap RetainCall fills. Sara — RetainCall's AI dispatcher — is the number you forward to when there's no human free. She answers every forwarded call in under a minute, holds a real conversation, and books the appointment straight into your calendar. Point your no-answer and busy forwards at her and nothing dead-ends, ever. It's $199/month flat — unlimited calls, no per-call fees, which is the whole reason a busy-season surge doesn't blow up your bill. If you want to see how that stacks up against a human answering service or a usage-billed AI receptionist, we lay it out plainly on the compare page, and there's a trade-specific rundown for HVAC shops at retaincall.com/for/hvac.

But set up the forwarding first — today, for free. Whatever you point it at, a call that rings out to nowhere is the one outcome you can rule out in ten minutes.

Or try it on your own line first — the free 7-day trial is at retaincall.com, no card required to start. Set your no-answer forward to point at RetainCall and watch what happens to the calls you used to lose.

RetainCall was built after watching contractor friends lose four-figure jobs to calls that rang out to nowhere — somebody had to just fix it. Reach us at support@retaincall.com. Related: The real math on missed HVAC calls · The one-truck owner's guide to not being the receptionist · Compare your answering options