You have a compatible phone system
Your 3CX, FreePBX or other SIP-enabled PBX works well, but the lines feeding it are costly, inflexible or approaching replacement.
Enterprise voice
Business SIP Trunks
Business SIP trunks on the IT Communications UK SIP network, with carrier interconnects, resilient routing, UK numbers and plans from £4 per channel.
UK-based expertiseSolutions designed around youClear migration planningLong-term technical support
SIP trunks, explained simply
Keep your phone system. Replace the expensive phone lines behind it.
A SIP trunk connects your existing business phone system to the public telephone network using your internet connection. IT Communications operates its own UK SIP network and maintains carrier interconnects to route calls beyond our platform; we are not simply reselling an anonymous third-party SIP service.
Your compatible PBX connects directly to our voice platform, giving our engineers visibility and control across the SIP service, routing, telephone numbers and carrier handoff.
For most organisations, that means lower ongoing costs, easier growth and a practical way to keep calls flowing when a site or connection has a problem.
Is it right for your business?
You probably need SIP trunks if…
The technology matters less than the problem it solves. These are the common reasons customers speak to us.
You need to add capacity quickly
Add concurrent call channels as your team grows, without ordering physical lines or rebuilding your telephone infrastructure.
Missing calls would hurt
Automatic failover can redirect inbound calls to another number if your PBX, power or internet connection becomes unavailable.
You want to keep your numbers
We can port most existing UK geographic, non-geographic and DDI numbers, so customers can continue calling you as normal.
What actually changes?
A modern connection behind the phone system your team already knows.
The phone system stays familiar. The connection becomes more flexible.
Your calls travel from your PBX, across suitable business connectivity, into our UK SIP platform and onward to fixed and mobile networks.
Learn about number porting →01Your phone system3CX, FreePBX or compatible PBX
→02Business connectivityBroadband or leased line
→03ITC SIP networkUK platform with resilience
→04Your callersFixed and mobile networks
Why businesses switch
More control over cost, capacity and continuity.
We plan the service around your phone system, expected concurrent calls and available bandwidth—not a one-size-fits-all bundle.
Reduce line and call costs
Pay for the channels you need, with low call tariffs and optional inclusive-minute packages.
Scale without physical lines
Increase or reduce channel capacity as demand changes, including seasonal and campaign requirements.
Build in call continuity
Route calls to an alternative destination when your on-site system or connection cannot receive them.
One accountable UK team
Number porting, SIP service, connectivity guidance and ongoing technical support from one provider.
SIP trunk pricing
Choose how you want to pay for calls.
One channel supports one concurrent call. Choose pay-as-you-use, 1,000 included minutes or unlimited minutes for each channel.
All packages include10 UK numbersFree number portingGold call tariffPrices exclude VAT
Pay-as-you-use
SIP
Per month / channel£4.00Per channel / concurrent call- No inclusive calls
- From 4 SIP channels
- Gold call tariff
- 10 UK standard numbers
- Free number porting
- 24-month contract
Most popular
SIP 1,000
Per month / channel£10.001,000 minutes per channel- 1,000 inclusive minutes per channel
- From 4 to 128 SIP channels
- Gold call tariff
- 10 UK standard numbers
- Free number porting
- 24-month contract
Maximum certainty
SIP Unlimited
Per month / channel£20.00Unlimited minutes per channel- Unlimited inclusive calls
- From 4 to 128 SIP channels
- Gold call tariff
- 10 UK standard numbers
- Free number porting
- 24-month contract
Unlimited-minute fair use
Unlimited packages include UK landlines (01/02) and UK mobiles, subject to a fair-use policy of 3,000 call minutes per channel per month. They are intended for normal business telephone use; call centres, telemarketers and resellers are excluded.
A managed move
Switch without unnecessary disruption.
We coordinate the technical checks, number porting and activation for a controlled move to your new SIP service.
- 01
Understand
We review your PBX, numbers, sites, connectivity and peak concurrent calls.
- 02
Design
We specify channels, resilience, routing and a suitable migration approach.
- 03
Test
The trunk is configured and tested with your compatible phone system.
- 04
Move
We coordinate number porting and activation, then remain available for support.
Common questions
What customers want to know before switching.
Do you operate your own SIP network?
Yes. IT Communications operates its own UK SIP network, with carrier interconnects for calls to and from fixed, mobile and international destinations. Our team manages the SIP service, routing and number delivery directly.
Can I keep my existing telephone numbers?
Most UK geographic, DDI and non-geographic numbers can be ported. We check portability before agreeing the migration plan.
Will I need a new phone system?
Not necessarily. SIP trunks work with 3CX, FreePBX and many modern SIP-compatible systems. We will confirm compatibility first.
How many channels do I need?
A channel supports one concurrent call. The right quantity is based on how many inbound and outbound calls your organisation makes at the same time—not simply your number of employees.
What is the difference between SIP and VoIP?
VoIP is the broad term for carrying voice communications over IP networks. SIP is a signalling method commonly used to connect a compatible business phone system to a voice provider. A SIP trunk is therefore one type of business VoIP service.
What internet connection does a SIP trunk require?
A SIP trunk needs suitable, stable IP connectivity with enough capacity for concurrent calls. Depending on the site and operational impact, that may be business broadband or a fibre leased line.
Can SIP trunks connect Microsoft Teams?
SIP Trunks and Microsoft Teams Direct Routing are separate services. We can discuss the appropriate Teams voice connection where Teams is the required user platform.
What happens if our internet connection fails?
Automatic failover can redirect inbound calls to an alternative number. For higher-dependency environments, we can also discuss resilient connectivity and routing options.
Do you offer unlimited SIP trunks?
Yes. SIP Unlimited includes UK landline and UK mobile calls, 10 UK standard numbers, free number porting and the Gold call tariff on a 24-month contract. A fair-use limit of 3,000 call minutes per channel per month applies, and call centres, telemarketers and resellers are excluded.
Start a conversation
Make communications one less thing to worry about.
Speak to an experienced UK specialist about the right approach for your organisation.