Frequently Asked Questions

A business phone system helps you make, receive and manage business telephone calls, whether you work alone, in one office or across several locations.

Unlike a basic telephone line, a business phone system can provide features such as call transfers, voicemail, opening-hours rules and ways to share incoming calls between colleagues. The available features depend on the system you choose.

Business phone systems can be operated on your premises or hosted by a provider. They may also support calling through Microsoft Teams or other applications. The right option depends on how your business works, what you already use and what you need to change.

Absolutely! You do not need several employees or a dedicated office to use business telephony.

A suitable system can give a sole trader or one-person business a business telephone number, voicemail and ways to handle calls when you are unavailable, including outside opening hours. Depending on the system, you can play recorded messages telling callers when you are open, where to find your business or how to contact you. Depending on the solution, you may be able to make and answer calls from a desk phone, computer or mobile device, presenting your business number rather than your personal mobile number.

You can start with a single-user arrangement and, where supported, add users and features to the same system as your business grows, without moving to another service. Options may include an auto-attendant, which greets callers and offers a menu of choices, or an AI receptionist that answers routine questions. Availability and costs depend on the solution.

Not necessarily. Cloud telephony is one way to run a business phone system, but it is not the only option or automatically the best fit.

An on-premises system may suit a business that wants local control, needs to retain particular equipment or integrations, or relies heavily on calls between people at the same site. For example, warehouses, large retail premises, hotels, bars/pubs and nightclubs may have demanding internal communications needs. That does not automatically mean they need an on-premises system: the right choice depends on how calls must work during connectivity or power failures and on the overall resilience design. SIP trunks may let you modernise the external telephone connection without replacing a compatible phone system. Where an existing system uses ISDN interfaces, an ISDN-to-SIP gateway may also allow it to connect to a SIP trunk. Compatibility and the functions supported must be checked before choosing this approach. Microsoft Teams can also be used as a business calling interface, with a suitable telephone service behind it.

Consider how you work, what you need your calls to do, your existing equipment, connectivity, resilience requirements and budget before choosing an approach.

The main difference is where the core phone system operates and who looks after it.

With an on-premises phone system, the central telephone system runs on equipment or infrastructure under your business's control. This can provide more direct control, but also means planning for its maintenance, lifecycle and resilience. A fault may require an engineer to visit, which can delay resolution. On-premises systems also commonly involve an upfront purchase or lease of the equipment.

With cloud or hosted telephony, the provider operates the central phone system away from your premises. Cloud services are commonly charged through recurring subscriptions. You still need suitable connectivity, local networking, power and devices where relevant.

Both approaches can support modern features and remote working, depending on the product and design. The better choice depends on your requirements, how your business operates during and outside normal working hours, and your technical, operational and commercial priorities, not simply whether a system is labelled 'cloud'.

No. The terms are related, but they describe different things.

VoIP (Voice over Internet Protocol) is technology for carrying telephone calls over a computer (IP) network. Cloud telephony describes a phone system whose central platform is hosted and operated away from your premises by a provider.

A cloud phone system commonly uses VoIP, but VoIP can also be used with an on-premises phone system or with SIP trunks connecting a compatible phone system or other telephony equipment to a telephone provider.

So choosing VoIP does not, by itself, mean you have to move your phone system to the cloud.

Yes. An on-premises phone system is one whose central equipment is operated at your premises. That does not mean everyone must use a desk phone or work in the same building.

Depending on the system, remote colleagues may be able to use supported desk phones, computer applications or mobile apps to make and receive business calls. They may also be able to keep their business extension and caller number when working away from the office.

These capabilities depend on the equipment, licences and network setup. Secure remote access, internet connectivity and resilience must be considered, particularly if the office connection or power fails. An on-premises system can support flexible working without automatically needing to be replaced by cloud telephony.

A SIP trunk is a telephone service that connects a compatible business phone system or other supported telephone equipment to the public telephone network over an internet or other suitable data connection.

It can replace traditional analogue (PSTN) or digital (ISDN) telephone lines while allowing a business to retain a suitable existing phone system. The phone system still manages users and features such as extensions, transfers and call routing.

A SIP trunk is the telephone service, not the broadband connection itself. Before replacing existing lines, check that your equipment is compatible and that the connection can reliably support your calls.

No. A SIP trunk provides a way to make and receive calls through the public telephone network. It does not, by itself, give your business a complete phone system.

Features such as extensions, voicemail, call transfers, opening-hours rules and call queues normally come from the connected phone system or another supported telephony service.

A SIP trunk can be useful if you want to retain a compatible existing phone system while modernising its external connection. If your equipment uses older telephone connections, a suitable gateway may sometimes allow it to work with the new service, subject to compatibility checks.

Some compatible broadband routers can also connect an ordinary analogue telephone, like a home phone, to an internet-based telephone service instead of a traditional wall socket. However, this does not mean every router supports a separately supplied SIP trunk. Internet providers may restrict the telephone settings on their supplied routers; replacing the router can be an option where the broadband service and intended telephone setup allow it.

Yes. With a suitable telephony configuration, Microsoft Teams can let you make and receive calls to ordinary telephone numbers from supported devices.

Using Teams for business calling involves more than installing the Teams application. The required calling functionality, licences where applicable, telephone numbers and a connection to the public telephone network need to be arranged.

The right setup depends on whether Teams will provide your main calling experience, work alongside an existing phone system or form part of a wider telephony solution. Available features and devices depend on the chosen configuration.

No. Choosing Microsoft Teams as the place where people make and receive calls does not automatically determine which provider supplies your telephone service or how calls reach the public telephone network.

Different connectivity and integration approaches are available, including Microsoft-managed calling options, supported operator connections and arrangements using a compatible telephony platform. Which options are available depends on your requirements, licences and the providers involved.

When assessing Teams telephony, consider your existing phone system, telephone numbers, call handling needs, resilience and support arrangements before selecting the underlying solution.

Yes. Fixed telephony describes the business telephone service, not a requirement to stay beside a fixed desk phone.

Depending on the system, employees may be able to make and receive business calls using desk phones, computers, web applications or mobile applications while working at home, on site or away from the office. Supported arrangements can also let them use a consistent business number rather than giving out a personal mobile number.

The available devices, features and call behaviour depend on the selected solution. Remote working also needs appropriate connectivity, security and a plan for what happens if internet or power is unavailable.

Fixed-Mobile Convergence (FMC) is a way of bringing your business phone system and mobile calling closer together, so you can use a consistent business telephone identity when working away from your desk.

For example, calls to your business number may reach you on a mobile device, and you may be able to make outgoing calls that show your business number rather than your personal mobile number.

There are different ways to achieve this. Some services integrate directly with a mobile network; others use an application on your mobile phone and offer similar day-to-day benefits. These are not necessarily the same service, so check how calls work when Wi-Fi or mobile data is poor, whether you need to change mobile provider, and whether an additional SIM or eSIM is required.

Yes, with a suitable business phone system. You may be able to receive calls to your business number on a mobile phone and make outgoing calls that show your business number to the person you are calling.

Depending on the service, this might work through a mobile application, call forwarding or a solution that integrates more closely with the mobile network. Some options let you keep your existing personal mobile contract.

Not every approach works in the same way. Before choosing one, check what callers see, how incoming calls are handled, whether you can separate business and personal calls, and what happens when mobile data or Wi-Fi is unavailable.

Not necessarily. You may need only a desk phone, only an application on your computer or mobile, or a combination.

A desk phone can be useful for a fixed workplace such as a reception desk, shop counter or office. A mobile app can help you answer and make business calls when you move around or work elsewhere, while keeping your business calling separate from your personal number where supported.

A mobile app can also be an alternative to a cordless (DECT) business phone, allowing staff to handle calls on a compatible smartphone while using other work apps, such as barcode scanning, stock management or product catalogues. Whether this is suitable depends on wireless coverage, the working environment, device management and the calling features supported.

The right mix depends on how your team works. Check which devices your chosen phone system supports, whether extra licences are required and how calls behave when internet or mobile connectivity is poor.

Hot desking means using a shared workspace rather than having a permanently assigned desk. With a phone system that supports telephone hot desking, a person can sign in at a compatible shared desk phone and use their own extension or calling settings.

It can still be useful in workplaces where people work different shifts or move between desks, such as offices, reception areas and shared operational spaces. It may reduce the need for a dedicated desk phone for every employee.

Not every phone system or handset supports the same sign-in features. If your team works mainly from laptops or mobile apps, you may already have the flexibility you need without telephone hot desking.

Traditional analogue (PSTN) and digital (ISDN) telephone lines are being replaced by services that carry calls over modern data connections. The right replacement depends on what your current line is used for.

For a business with a phone system, options can include cloud telephony, a new on-premises phone system or a SIP trunk connecting a compatible existing system. A small business using an individual phone may have simpler replacement options, depending on its equipment and provider.

Before making a change, check whether the existing phone line also supports a fax machine, alarm, lift phone, telecare device, panic button or other equipment. These may need a different replacement service or equipment changes. Do not assume an ordinary internet-based telephone service will support every device.

Further reading: UK Digital Switchover article (internal content reference; Website link to be added when the destination is confirmed).

No. The withdrawal of traditional analogue (PSTN) and digital (ISDN) telephone services does not mean every business must move its phone system to the cloud.

You may be able to keep a compatible on-premises phone system and replace its external telephone connection with a SIP trunk. Some older systems may work through a suitable gateway, but this needs checking. Alternatively, you can consider a new on-premises system, cloud telephony or another replacement that meets your requirements.

The best option depends on your existing equipment, how staff make and receive calls, your internet connectivity, resilience needs and budget. Check any other equipment connected to the old lines before agreeing a migration.

Further reading: UK Digital Switchover article (internal content reference; Website link to be added when the destination is confirmed).

In many cases, yes. Number porting is the process of transferring an existing telephone number from one provider or service to another, allowing you to keep using the number when you change telephone arrangements.

Whether a number can be transferred depends on the number type, current and new providers, service configuration and applicable porting rules. You should confirm this before agreeing to replace your existing service.

Make a list of every number your business uses, including main numbers, direct-dial numbers and numbers attached to specialist equipment. Check your telephone bills for the numbers listed and contact your current provider if you need to confirm which numbers and services are on your account. Ask your new provider which numbers can move, what will happen during the change and whether any numbers need a separate plan.

Further reading: UK Digital Switchover article, number-porting section (internal content reference; Website link to be added when the destination is confirmed).

Number porting moves an existing telephone number to a new provider or service so customers can continue calling the same number.

Typically, your new provider checks the number details, submits the transfer request and arranges a changeover date with the organisations involved. You may need to provide information about the current account, the numbers to be moved and any services linked to them.

The time required varies with the provider, number type and complexity of the transfer. Plan the changeover, confirm how incoming and outgoing calls will work during the move and test the numbers afterwards. Keep your existing service active until the port has completed and your provider confirms it is safe to cancel.

Do not cancel your existing telephone service before all associated number-porting orders have completed. Cancelling it prematurely can cause outstanding porting orders to be cancelled, putting your business telephone numbers at risk.

Arrange the transfer through your new provider and wait until every number-porting order is confirmed complete. After porting, the previous provider should normally arrange termination of the transferred service, but check directly that this has happened and whether any other services remain active.

Before agreeing to cancel anything, also check whether the existing account supplies broadband, alarms, fax, other numbers or services that still need to work.

Possibly, but do not assume that an existing fax machine will work reliably with a new internet-based telephone service.

Fax machines were often designed for traditional telephone connections. Some replacement services and equipment can support faxing, but compatibility and reliability depend on the machine, the connection and the provider. A fax machine that appears to work in one test may not handle every document or destination reliably.

Before changing the line, check whether you still need to send or receive faxes. Ask your telephone and equipment providers to confirm a supported solution, which might involve a suitable adaptor or an electronic fax (eFax) service that sends and receives faxes digitally, without relying on a traditional fax machine. Check that the option supports your business requirements. Test sending and receiving before retiring the existing service.

Check every device that uses your existing telephone line before the line is changed or cancelled. A phone line may support more than ordinary calls.

Examples include intruder/burglar and fire alarm signalling, lift emergency phones and remote elevator monitoring, warden-call systems, lone-worker alarm devices, panic buttons, PDQ/card-payment terminals and other equipment that automatically contacts a monitoring centre or service provider.

These devices may not work correctly with an ordinary replacement telephone service, even if a telephone handset does. Contact the company that supplies or maintains each device, or its monitoring service, and ask which replacement connection is supported. Arrange any equipment changes and testing before the old line is removed. Pay particular attention to safety-critical equipment and any backup power requirements.

Not always. VoIP means making telephone calls over a data network rather than a traditional telephone line. Your existing broadband may be suitable, but that depends on how it performs and how many calls you need to make at the same time.

Call quality depends on more than advertised download speed. A reliable connection, sufficient capacity, your office network, Wi-Fi where used and the configuration of your router can all make a difference.

Before switching, review how many people will be calling simultaneously, where they will work and what else uses the connection. If telephone calls are critical to your business, discuss a backup connection or alternative calling arrangements as well. Your provider should confirm the connectivity requirements of the selected system.

It depends on your telephone system and how it is connected. If calls rely on your premises' internet connection, a failure may stop affected desk phones and applications from making or receiving calls.

Some systems can be set up to divert incoming calls to another number, ring devices connected elsewhere or use an alternative internet connection. A supported business calling app on a smartphone may also keep working over an independent 4G or 5G mobile data connection, provided mobile coverage, the app and the telephone service are available. These options are not automatic with every service. Some may need to be configured in advance, and others may not work if particular equipment or services also fail.

Ask what happens to incoming calls, outgoing calls and staff working on site when the connection is lost. Agree a practical backup plan and test it before relying on it.

Emergency calls: Calls to 999 and 112 through the business phone system may be unavailable during a broadband, local network, provider-platform or equipment outage. If the system is unavailable, use a mobile phone's native dialler or another independent working service, rather than relying on the business calling app for emergency calls. Mobile access requires a working mobile network and suitable service; it cannot be guaranteed. Always tell the emergency call handler your exact location and a reliable callback number.

A power cut can affect business calling even when the phone system itself is hosted elsewhere. Desk phones, broadband routers, network switches, Wi-Fi equipment and other devices at your premises may stop working without electricity.

An on-premises phone system may also lose power unless it has a suitable backup supply. Depending on the chosen solution, calls might still reach an alternative site or a separately connected mobile device, but this needs to be planned and tested.

If telephone availability matters during an outage, check which equipment needs backup power, how long it should operate and how incoming calls will be handled. Do not assume that ordinary business phones or internet-based calling will remain available during a power cut.

Emergency calls: Calls to 999 and 112 may be unavailable when required equipment or services lose power. During an outage, use a mobile phone's native dialler or another independent working service, rather than relying on the business calling app. This depends on a working mobile network and suitable mobile service, and cannot be guaranteed. Always tell the emergency call handler your exact location and a reliable callback number. Discuss emergency-calling resilience with your provider, especially if anyone depends on the business telephone service as their means of contacting emergency services.

Many business phone systems can be configured to call the UK emergency numbers 999 and 112, but you should check how emergency calls work on your particular service and devices.

Internet-based and on-premises systems can depend on electricity, broadband, local network equipment, the telephone system and the provider's service. If a required part fails, emergency calls through the business system may not work.

If the business phone system is unavailable during an emergency, use a mobile phone's normal telephone dialler or another independent working telephone service. Mobile access depends on an available mobile network and cannot be guaranteed.

When calling emergency services, always tell the call handler the exact location of the emergency and a reliable number on which they can call you back. Ask your provider to explain your service's emergency-call arrangements and what alternatives you should maintain, especially where staff rely on the business phone system for emergency access.

When you call 999 or 112 from a business phone system, the location information available to emergency services may come from the address recorded against the telephone number, the service or the location assigned to the device.

That recorded address might not be where you actually are. For example, you may be working from home, travelling or using a phone or application moved from its registered site. Even a desk phone can have outdated location records after a move.

Always tell the emergency call handler exactly where the emergency is and confirm a reliable callback number. Do not assume that the address or number displayed to them is correct.

Keep your business's registered addresses and relevant device-to-site details up to date. Tell the person who administers your phone system or your service provider before moving equipment or changing work locations, so they can check what needs updating. If working outside the UK, use locally appropriate emergency-calling arrangements rather than relying on a UK business phone application.

These terms describe three different jobs performed by a business phone system.

Call handling is what someone can do with a call, such as answering it, putting it on hold, transferring it to a colleague or sending it to voicemail.

Call distribution is how incoming calls are shared between people or teams. For example, several phones might ring together, or callers might wait in a queue for the next available person.

Call routing is the set of rules that decides where a call goes. A business might send calls to reception during opening hours, offer a menu of departments or direct out-of-hours calls to voicemail or another number.

These functions can work together, but they are not interchangeable. Which options are available depends on the phone system you choose.

A business phone system can help send incoming calls to the right person, team or destination rather than relying on someone to answer every call manually.

Depending on the system, you may be able to route calls by opening hours, the telephone number dialled or a caller's selection from an automated menu, often called an auto-attendant. Calls may go to a reception team, ring group, hunt group, queue, voicemail or an alternative number. Some systems can redirect calls when a team is busy or no one answers.

For example, a shop could send calls to staff during opening hours and play a recorded message when it is closed. A business with several departments could let callers choose who they need.

Available rules, announcements, queues and fallback options vary by product and licence. Decide what should happen during busy periods, outside opening hours and during an outage before setting up the call flow.

Some business phone systems offer call recording, either as a built-in feature or through an additional service. Others do not, or offer recording only for certain devices, users or types of call.

Businesses may want recordings for training, reviewing customer conversations or maintaining records. Before selecting a system, check which calls can be recorded, whether recording is automatic or started by a user, who can access recordings, and how recordings are stored, retained and deleted.

Recording telephone conversations also raises privacy and data-protection responsibilities. You should establish a lawful and appropriate recording process, including any required notices and access controls, before switching it on. Do not assume that purchasing a recording feature makes its use automatically compliant.

Your chosen provider should confirm the feature's technical capabilities and commercial terms; the appropriate recording policy requires separate consideration.

Some business phone systems provide call history and reporting to help you understand how calls are handled. The detail depends on the product, licence and any additional reporting service.

Basic records may show when a call took place, its duration and whether it was answered or missed. Other systems may offer team or queue reports, such as call volumes, waiting times, abandoned calls and how quickly calls are answered.

These are not all the same thing: an individual user's call history, a system-wide call record and a contact-centre performance report may require different features or permissions.

First decide whether reporting or call analytics would be useful to your business at all. What decisions would the information help you make, and would you actually use it? Simple missed-call records may be sufficient for some businesses; advanced reports may bring little value if no one needs or reviews them. Avoid paying for an additional reporting service simply because the features look interesting.

If reporting would be useful, identify what you need to measure, who should see it, how far back the information must be available and whether you need to export it. Ask the provider to demonstrate the reporting included in your proposed configuration and identify any extra cost. Call data can be personal data, so access and retention should also be considered.

Possibly. Some business phone systems can work with customer relationship management (CRM) software, Microsoft 365 or other business applications. The integration available depends on both systems, their versions, licences and how they connect.

For example, a supported CRM integration might help staff start a call from a customer record or display matching customer information when a call arrives. Some services may also support directory-related functions, subject to the specific integration. These are examples of potential functions, not features included with every phone system.

Microsoft Teams calling is a separate design decision. Using Microsoft 365 does not automatically give a business public telephone calling through Teams, and connecting a telephone system to Teams may involve additional products, licences or configuration.

List the applications and specific tasks you want to connect. Ask for a supported integration and a demonstration of the exact workflow, including permissions, data handling, ongoing maintenance and any extra charges, before committing.

A business phone system may offer controls for unwanted incoming calls and for unauthorised or fraudulent outgoing calls. These are different problems and usually require different safeguards.

Depending on the service, incoming-call options might include blocking particular numbers, screening calls, routing unknown callers differently or using provider-supported nuisance-call controls. Some systems can block calls where the caller's number is withheld (anonymous calls), but use this carefully: legitimate customers and organisations may also withhold their numbers. Number blocking has limits because caller numbers can be falsified, and over-restrictive rules may stop genuine customers reaching you.

For unsolicited sales calls, businesses can consider registering eligible numbers with the Corporate Telephone Preference Service (CTPS); sole traders and some partnerships may instead use the Telephone Preference Service (TPS). These opt-out registers apply to certain unsolicited live marketing calls, not every unwanted or fraudulent call, and they do not provide a technical call-blocking guarantee. See the Information Commissioner's Office guidance on business-to-business marketing for details.

For outgoing calls, sensible precautions can include strong account credentials, restricted international or premium-rate dialling, carefully controlled administrator permissions and prompt investigation of unusual calling activity. Some providers may offer usage monitoring or alerts, but these should not be assumed to be available. The precise controls available vary by supplier and system.

Ask your provider which safeguards can be configured, who monitors alerts and what happens if misuse is suspected. No single setting can guarantee that unwanted calls or telephone fraud will be prevented.

Implementation is more than supplying a phone or activating a subscription. The work required depends on your existing telephone service, number-porting arrangements, premises, users and the system you choose.

A typical project may involve reviewing requirements, checking internet and network readiness, designing the call flow, arranging telephone numbers or number transfers, configuring extensions and devices, and testing incoming and outgoing calls. User guidance, administrator handover and a plan for switching from the old service may also be needed.

Do not assume all these activities are included in the standard subscription or installation price. Some may be supplied by the communications provider, an installation partner or your own IT team. Specialist work, equipment and training may be separately chargeable.

Before agreeing to proceed, ask for a written implementation scope identifying who does each task, what you must provide, any exclusions, proposed timescales and how successful handover will be confirmed. Include emergency-calling configuration and location information in the checks relevant to the chosen service.

The advertised price for a business phone system may not cover everything needed to deploy and use it. The overall cost depends on the provider, licences, equipment, calling plan and the services your business needs.

Potential additional costs include desk phones or headsets, broadband or network upgrades, installation, configuration, telephone number transfers, training, specialist integrations, call recording, advanced reporting and ongoing administration. Some products include certain functions in the base service; others charge separately or require a higher licence tier.

Call charges and usage allowances also need checking. Calls outside an included allowance, international destinations or certain number types may be billed differently. Contract commitments, equipment arrangements and any change or termination charges should be confirmed in the applicable offer and terms rather than assumed.

Request a written quotation that distinguishes one-off charges, recurring subscriptions, usage-based charges, optional features and any excluded work. Compare the total expected cost for your actual requirements, not just the headline monthly price.