Ring a small business at 12:45 on a weekday, or ten minutes after the office closes, and listen to what happens. The phone rings out, or the call lands in the voicemail of someone on leave. Few callers leave a message. A prospect comparing suppliers rings the next one on the list.
Call forwarding is the oldest fix. On a mobile it takes one of five codes. In a business phone system it becomes a set of rules: who rings first, who covers lunch, where calls go after 17:30 and what happens when nobody picks up. The two behave very differently once a team is involved, because a code set on one person’s handset is invisible to everyone else, including whoever later has to work out why calls stopped arriving.
Below: the five codes and where they stop being enough, how forwarding works in Onoff Business, three setups for common teams, and how to find and switch off the divert nobody remembers setting.
What is business call forwarding?
Call forwarding sends an incoming call to a different number before anyone answers. In the UK it is just as often called call diverting. Every forward pairs a condition (all calls, or only when you are busy, do not answer or cannot be reached) with a destination: another mobile, a colleague, a landline or voicemail.
Business call forwarding applies the same idea to numbers the company owns, rather than to one person’s SIM. The rules sit in a phone system, so they can ring several people at once or in turn, change with the time of day, and be seen and edited by an administrator. Forwarding acts before a call is answered. Moving a call someone has already picked up is a transfer, and Onoff Business handles that separately with cold and warm transfers.
Why businesses forward calls
- Missed calls become lost enquiries. Most inbound calls come from someone who wants an answer now: a quote, a booking, a viewing. Voicemail asks them to wait, and many will not.
- The published number stays put while people move. The number on the website, the van and the invoice does not change when the team works from sites, home or client offices.
- Absence and busy lines stop showing. A colleague or a group picks up when one person is on leave, off sick or already on a call.
- Out-of-hours calls get an answer. An on-call engineer, or a voicemail that gives the next opening time, serves a caller at 21:00 on a Friday far better than a phone that rings out.
- Client relationships stay with the company. When calls run through business numbers and rules the company controls, a resignation does not take the contacts with it.
How to forward calls on a mobile: the five codes
Every mobile network in the UK and Europe uses the same GSM codes, on iPhone and Android alike. Type the code, the destination in international format (+44 for the UK, dropping the leading 0) and the hash key, then press call. The phone confirms on screen.
Divert | Switch on | Switch off | Check |
|---|---|---|---|
All calls | **21*+44number# | ##21# | *#21# |
When unanswered | **61*+44number# | ##61# | *#61# |
When busy | **67*+44number# | ##67# | *#67# |
When unreachable | **62*+44number# | ##62# | *#62# |
Every divert at once | ##002# |
To send every call to 07700 900123, dial **21*+447700900123#. The no-answer timer can be set between 5 and 30 seconds. Vodafone documents adding *10* and the number of seconds to the no-answer code, so **61*+447700900123*10*15# diverts after 15 seconds of ringing.
On iPhone and Android
On an iPhone, go to Settings, then Apps, then Phone, then Call Forwarding (Settings, then Phone, on iOS 17 and earlier). The menu only forwards all calls; the conditional types still need the codes. On Android, open the Phone app, tap the three-dot menu, then Settings, and look for Call forwarding under Calls or Supplementary services, where all four conditions usually appear.
On a landline
Most UK landlines use single-star codes: *21* followed by the number for all calls, *61* for unanswered calls and *67* when the line is engaged, cancelled with #21#, #61# or #67#. The no-answer timer is fixed by the provider, 15 seconds on Vodafone and 21 seconds on TalkTalk.
Where phone-level forwarding falls short for a business
Divert codes were designed for one person and one SIM. A team reaches their limits quickly.
- One destination per condition. A divert sends the call to a single number. It cannot ring three colleagues at once, or move to the next one when the first is busy.
- No clock. Network diverts are either on or off. Sending calls to the office in working hours and to voicemail after 17:30 means someone keying in codes twice a day.
- Invisible to the business. The rule sits on an employee’s SIM. Nobody else can see it, and it usually comes to light when a customer complains.
- Every forward is a second call. The network places a new call to the destination and bills the forwarding line for it, at that line’s rate.
- No record. A forwarded call leaves no trace in the CRM, and a missed one leaves none at all.
- Tied to a person. When the employee leaves or the contract ends, the number and its diverts go with the SIM.
How to forward business calls with Onoff Business
Onoff Business gives each employee a business number in an app on the phone they already carry, with the numbers owned and managed by the company from an admin interface. Forwarding works at three levels: a single number, its working hours, and a shared number that routes calls across the team.
Forward a number to a colleague or another phone
Each user sets forwarding in the app, number by number, to any contact or phone number. To forward your calls with Onoff Business, follow these steps:
- Open the app and tap the menu icon (☰) in the top-left corner.
- Select the number you want to forward.
- Tap Number settings, then Call Forwarding, and switch the toggle on.
- Choose a contact or type the destination number.
- Choose what to forward: all calls, or only missed calls.
Switching the toggle off stops forwarding. The app keeps the last destination, so turning holiday cover back on takes two taps.
Set the hours a number takes calls
The On/Off schedule switches a number off automatically outside the hours you choose. In the app, open the menu, tap Options under the number, then Number settings and On/Off Scheduling. In Off mode, calls go to voicemail and texts are held until the number is back on, so evenings and weekends need no forward at all. Each number can keep its own hours, for example a sales line and a support line.
Ring the whole team with the Greeting IVR
For a number the team shares, such as a main line, a sales line or a branch number, there is Greeting IVR . An IVR number belongs to the organisation rather than to one user, and an admin builds its call flow in the admin interface.
- Assign a Greeting number and set its time zone.
- Create shifts by day and time (up to ten, each at least 15 minutes long), plus a main flow for the hours no shift covers.
- Build each flow from blocks: a welcome message, a keypad menu (“For sales, press 1”), Forward to, Voicemail or Hang up.
- Activate the Greeting.
The Forward to block is where forwarding turns into routing, or what older phone systems called a hunt group. It rings up to 15 colleagues at once, or one after another with each phone ringing for 5 to 40 seconds before the next, and it can skip anyone already on a call. If nobody answers, the flow moves to the next block: a second group, or a voicemail delivered to the colleagues who will follow it up. Every call is logged, reports export as CSV, Excel or PDF, and only admins and owners can change the flow, so the rules do not drift.
Greeting is part of the Advanced plan, which includes one Greeting number. Text-to-speech messages need the Max plan.
Answer at a desk without forwarding
A user can be signed in on up to three devices at once, such as their phone and the web app on a laptop, so taking calls at a desk needs no divert. The desktop app for Mac and Windows runs in the background, so calls come through even with Chrome closed.
Hand over a number when someone leaves
Forwarding a leaver’s mobile to their manager works until the SIM contract ends. In Onoff Business an admin reassigns the number to another employee, and its call history, voicemails and messages stay with it.
See what happened to every call
Calls through Onoff Business appear in call statistics and, with the HubSpot or Pipedrive integration, on the contact record, logged as connected, missed or voicemail so someone can call back.
On cost: a call routed to a colleague’s app stays inside the platform. A call forwarded to an outside number is an outgoing call on your plan, and destinations outside the plan, or usage beyond its monthly allowance, are paid from call credits.
Three setups that work
An estate agency with negotiators out on viewings
The branch number is on every board and portal listing, but on a Saturday one person is in the office and three negotiators are out. An IVR shift for Saturday rings the office first, then the negotiator who covers the area, then the rest of the team, each for 15 seconds. A second shift from 17:30 plays a short message with the next opening time and takes a voicemail. A buyer ringing from outside a property reaches someone who knows the area, and nobody hands out a personal mobile. More on our real estate page.
An inbound sales line
Four account executives share one sales number. A Forward to block rings all four at once and skips anyone on a call, so whoever is free answers and the prospect waits seconds. If nobody picks up, a second block rings the SDR, and only then does the call reach a voicemail sent to the whole team. In HubSpot, each call lands on the contact record as connected, missed or voicemail, so a missed enquiry has an owner by the end of the day.
A trades firm with engineers on site
Each engineer has a business number in the app. An engineer in a loft or under a floor cannot take a call, so their number forwards missed calls to the office coordinator, who books the job before the customer rings the next firm. In the evening the On/Off schedule sends calls to voicemail, except for the engineer on call that week.
How to turn off call forwarding, and find the divert you forgot
If calls have stopped reaching a phone, check for a forgotten divert first. Dial *#21#, *#61#, *#67# and *#62#: each shows whether that divert is on and where it sends calls. Then switch off whatever you find.
Where the divert is set | How to turn it off |
|---|---|
Any UK or European mobile | ##002# cancels every divert. ##21#, ##61#, ##67# or ##62# cancels one. |
iPhone settings | Settings > Apps > Phone > Call Forwarding, switch off. This only clears the all-calls divert: one set with a code stays on until you dial ##002#. |
Android settings | Phone app > Settings > Call forwarding, then disable each condition. |
UK landline | #21#, #61# or #67# |
Onoff Business app | Number settings > Call Forwarding, switch the toggle off. |
Onoff Business Greeting | An admin edits the flow. Deactivating a Greeting stops the flow altogether and calls show as missed, so change the shift rather than switching it off. |
Holiday diverts are the usual culprit. Put an end date in the calendar when you set one, and check business mobiles once a quarter.
Call forwarding in the UK
The codes behave the same on EE, O2, Three and Vodafone. Vodafone describes diverts as going to another UK landline or mobile, so do not count on an international destination, and it takes diverted calls out of your minutes allowance, charging standard rates once that runs out. Landlines vary: TalkTalk, for instance, asks customers to add Call Divert to the account before the codes work.
Openreach closes the analogue phone network on 31/01/2027 and has said the date will not move again. On 24/09/2026 it estimated that around 1.2 million lines were still on it, about 350,000 of them at business premises; lines that miss the deadline may move to EVAc, a temporary emergency service Openreach calls limited and more expensive than digital alternatives. A divert set on an analogue line goes with the line. Ask your provider how forwarding works on the digital replacement (on BT Digital Voice the 21, 61 and 67 codes still work), and see our guide to the PSTN switch-off for what else to check before the deadline. Teams that already answer on mobiles can publish a UK business mobile number in the Onoff Business app instead, and route it there.
It is call forwarding applied to numbers a company owns, set in a phone system rather than on one employee’s SIM. The rules can ring several colleagues, follow working hours and be managed by an administrator.
Yes. “Divert” is the usual word on UK networks and landlines; “forwarding” is more common in phone system software. Both send a call elsewhere before anyone answers.
Not with mobile codes, which allow one destination per condition. In Onoff Business, an IVR number rings up to 15 colleagues at once or in a set order.
Yes. In Onoff Business, IVR shifts give each time of day its own flow, and the On/Off schedule sends an individual number to voicemail outside the hours you set.
Yes, for diverts set with network codes, which the network holds. Unconditional and unreachable diverts work with the phone switched off or flat.
Usually not. They may hear a slightly longer ring while the second call connects. Nothing is announced unless you set a welcome message or a menu.
Who picks up when you can't?
Forward business calls to colleagues, set working hours and send the rest to voicemail, all from one app.
