A modern business phone service combines a public telephone number with a delivery method. The number can route to a SIP trunk or 3CX system, a hosted or cloud phone extension, or a call-forwarding destination such as an existing UK mobile.
What is a business phone system?
A business phone system manages how inbound and outbound calls are presented, routed, queued, transferred and answered. It may be installed on premises, hosted in a data centre, delivered as a cloud service or built around a simple virtual number and call divert.
Common features include auto attendants, call queues, hunt groups, voicemail, call recording, opening-hours routing, extension dialling, reporting and integrations. The exact features depend on the selected platform and service plan.
What is VoIP?
Voice over Internet Protocol, usually shortened to VoIP, carries voice signalling and audio using IP networks. VoIP can connect desk phones, softphones, mobile applications, session border controllers, PBXs and provider networks.
A VoIP number is not tied to one physical copper line. The number can normally route to the configured service wherever the required network, device and security controls are available.
Hosted phone system, cloud phone system and cloud voice
These terms commonly describe a business phone platform operated away from the customer’s premises. Users connect through supported SIP phones, software clients or mobile applications while the provider or platform operator maintains the central call-control service.
Hosted telephony can suit organisations that want extensions, call routing and business features without maintaining an on-premises PBX. “Cloud voice” is a broad commercial term and should always be checked against the actual features, resilience, support and call charges included.
What is a SIP trunk?
A SIP trunk connects a business phone platform to a telephone network using the Session Initiation Protocol. It can deliver one or more DDI numbers to an IP-PBX, 3CX deployment, SBC or other compatible voice system.
The design may use registration credentials or IP authentication. Concurrent-call limits determine how many calls can be active at the same time. UKDDI trunk tiers define separate inbound and outbound limits, which must also be applied on the carrier, SBC or PBX platform. Firewall policy, media routing, codecs, encryption, fraud controls and resilience should be agreed before activation.
What is a SIP trunk call package?
A SIP trunk call package adds either pay-as-you-go outbound calling or a monthly allowance of included minutes to a SIP trunk. The package is separate from the telephone-number rental and concurrent-channel charge.
Before ordering, check which UK landline and mobile destinations are included, whether unused minutes expire, the out-of-bundle rates, any fair-use restrictions and whether the allowance is applied per trunk, account or user. UKDDI records the selected package and its terms with the order.
DDI, DID and virtual phone numbers
DDI usually means Direct Dial-In or Direct Inward Dialling. DID is the equivalent term commonly used internationally. A DDI number allows an inbound call to reach a specific team, extension, call queue, customer service route or application.
A consecutive DDI block is useful when a business needs a range of related numbers. A single virtual phone number is useful for a main business line, local presence, campaign, department or temporary service.
Using UK phone numbers with 3CX
3CX is a business communications platform that can receive telephone numbers through compatible SIP services. The UKDDI checkout can collect SIP routing information, but the exact 3CX configuration, SBC design, supported features and security requirements must be confirmed during provisioning.
Compatibility wording does not mean every feature or deployment model is automatically supported. The responsible administrator should verify the current 3CX version, network design, authentication, inbound rules, caller ID and emergency-calling arrangements.
Landline divert, mobile divert and call forwarding
Call divert sends inbound calls from the selected business number to another UK telephone number. It is often the fastest way to launch a new local or national number because the customer can answer using an existing mobile or landline.
Forwarded calls normally attract usage charges. Businesses should consider caller identification, voicemail behaviour, simultaneous calls, out-of-hours routing and whether a more complete hosted or SIP service will be needed as call volumes grow.
Number porting
Number porting moves an existing telephone number between service providers where the number, losing provider, account information and gaining service meet the relevant requirements. Porting is different from buying a new number and may require evidence of ownership and an agreed migration date.
Do not cancel the old service before the port is accepted unless the providers have specifically instructed you to do so. Existing broadband, alarm, lift, fax, payment-terminal or other services associated with a line should be checked before any cancellation.
Which delivery option should I choose?
Questions to ask before ordering
- Which public number or DDI block is required?
- How many simultaneous inbound and outbound calls are expected?
- Will calls route to 3CX, another PBX, hosted phones or a mobile?
- Are call recording, queues, auto attendants or opening hours required?
- What resilience and internet connectivity support the phone service?
- Who is responsible for emergency-calling location information and testing?
- What setup, monthly rental, channel and usage charges apply?