Retain a compatible PBX
Review the platform, software version and existing support arrangements before deciding how the service will connect.
Voice connectivity for your PBX · Designed around your business
Keep what works.
Modernise the connection.
Explore internet-based calling for a compatible phone system, with capacity, numbers and continuity planned together.
Scope agreed around your business · One point of contact
Calling over an IP connectionPBX · Interconnection · Provider
SIP trunks, explained
What are SIP trunks?
Your existing phone system.
A digital route for calls.
SIP trunks connect a compatible business phone system to a telephony provider over an IP connection. They provide a route for inbound and outbound calls without relying on traditional telephone circuits.
Radian helps review the PBX, supported interfaces, numbers and calling patterns before proposing a service. Compatibility, maintenance, security and the wider business case determine whether retaining the system is the right choice.
See the bigger picture →Built around the work you do
A modern calling route.
A considered use of your PBX.
The features that matter, with the practical details made clear.
Calling capacity
Size concurrent calling around actual usage and busy periods, with the trunk and platform limits confirmed.
Business numbers
Check transfer eligibility and required number presentation, routing and destinations.
Secure interconnection
Plan firewall policy, authentication and any required SBC alongside the provider’s connection requirements.
Continuity options
Review backup connectivity and supported diversion or alternative routing for important numbers.
Coordinated support
Make ownership clear across the PBX maintainer, connectivity provider and telephony service.
Service availability, equipment, features, licences and support scope are confirmed in your proposal. Optional services are priced and agreed separately.
The picture, made clearer
Your PBX.
A digital route for calls.
A simplified service view. The components and responsibilities are agreed around your requirements.
- 01Your compatible PBXExtensions and local call handling
- 02Agreed interconnectionNetwork, firewall and any SBC
- 03Telephony providerCalls to and from telephone numbers
Illustrative service view. The components, features and responsibilities depend on the agreed setup.
Make an informed choice
Choose the setup around your work.
Compatibility first
Check the PBX model, version, available interfaces and vendor support. Some systems require changes or additional components.
Capacity and commercial terms
Compare concurrent calls, numbers, usage, destinations and contract terms together. Capacity and call allowances are different things.
The whole call path
Phone devices, local networking, the PBX and internet access all affect the service. Include them in the support and continuity plan.
The practical details
Keep the change
under control.
A SIP migration should preserve the intended calling experience while changing the connection behind it.
Plan your setup ↗Record the current setup
List numbers, call routes, platform access and any specialist devices or services that depend on existing lines.
Prepare before transfer
Configure the agreed service and test representative calls before moving important published numbers.
Verify the changeover
Check inbound and outbound calls, caller ID, transfers and the agreed fallback arrangements.
From enquiry to everyday use
A clearer path, with Radian.
- 01
Review
Check the PBX, existing numbers and calling demand.
- 02
Design
Agree capacity, interconnection and continuity.
- 03
Prepare
Configure supported components and test calling.
- 04
Transfer
Coordinate eligible numbers and complete the handover.
A little more clarity
SIP trunks,
answered.
Have a question about your setup?
Tell us what you want to achieve.
Will SIP work with any telephone system?
No. Compatibility, software support and provider requirements need checking. An SBC or another supported component may be required.
Can we keep our numbers?
Transfers depend on eligibility and the providers involved. We review the details and coordinate the date before existing services are cancelled.
How many channels do we need?
The requirement follows simultaneous calling demand rather than simply the number of extensions. We review busy periods and growth.
Does SIP replace the PBX?
No. SIP trunks provide connectivity; your compatible PBX continues to handle its phone-system functions.
Will it reduce our costs?
We compare the complete proposed service with the existing arrangement. Savings depend on capacity, usage, equipment and contract terms.
What if the office connection fails?
Alternative access and supported diversion can be considered. Their availability, addressing and behaviour need planning and testing.
UK-wide service enquiries
SIP trunks across the UK.
SIP trunking should be planned with the PBX, connection and UK business numbers it will support. Check compatibility, call capacity, security, emergency-calling details and transfer arrangements before the agreed cutover.
Based in Charlwood, we welcome enquiries nationwide, with a particular focus on Horley, Crawley, Gatwick, Surrey, Sussex and London. Delivery, availability and any site attendance are confirmed for your chosen service.
Let’s talk
Let’s review your
next calling connection.
Tell us about your current setup, priorities and plans. We’ll help you work through the next steps.
hello@RadianNetworks.co.uk