SIP trunking
Keep your platform. Replace the lines behind it.
SIP trunking connects the system you already operate to the public telephone network over IP. Same extensions, same call flows, same handsets — different, and considerably more flexible, connectivity underneath.
Diagram: your existing PBX connects over a SIP trunk with a set number of concurrent channels to the public network, with a failover site behind it.
What it solves
Physical lines price capacity you rarely use.
A traditional circuit sells you a fixed number of channels whether you need them or not, takes weeks to change, and ties your phone system to a building. A SIP trunk decouples all three: capacity becomes a number you adjust, and the platform stops caring where it lives.
- Scale channels to the demand you actually have.
- Keep the PBX, handsets and dial plan you already run.
- Stop tying voice capacity to a specific building.
- Reroute traffic to a second site when the primary is unreachable.
How it works
Three things happen to every call.
We check compatibility
Your PBX or platform, its SIP capabilities and how it authenticates.
The trunk is provisioned
Channels, numbers and authentication configured against your system.
Traffic cuts over
Inbound and outbound calls move to the trunk, with the old path available until you are satisfied.
Capabilities
What you can build with it.
Availability of individual capabilities depends on your setup and destinations. We confirm what applies before anything is configured.
- Concurrent channels
- Capacity sized to your real peak, adjustable as the business changes.
- Inbound and outbound
- One trunk carrying both directions, with numbers attached to it.
- Authentication
- IP-based allowlisting or SIP registration, whichever your platform expects.
- Codec support
- Negotiated with your platform. We confirm what your specific system needs.
- Failover routing
- A secondary destination for inbound traffic when the primary endpoint is unreachable.
- Number attachment
- Geographic, non-geographic and toll-free numbers delivered down the same trunk.
Example trunk configuration
A route you could read out loud.
One trunk, a channel limit, a primary endpoint and a defined secondary.
Route definition
Illustrative- Platform
- Your existing PBX, unchanged
- Channels
- Sized to your real concurrent peak
- Auth
- IP allowlist or SIP registration
- Numbers
- Geographic and toll-free on the same trunk
- If down
- Inbound fails over to a second endpoint
An illustrative example. Your route is written with you before anything is configured.
Use cases
Where it earns its place.
Replacing legacy circuits
Keep a PBX that works and retire the physical lines around it.
Multi-site businesses
One trunk serving several offices instead of lines terminating in each.
Seasonal capacity
Businesses whose call volume triples for part of the year and should not pay for that year-round.
Coverage & compatibility
Will it work where you need it?
Destinations, number types and endpoint compatibility vary. Send us the specifics and we'll confirm what is available rather than publish a list that may not hold for your case.
Works alongside
- Business VoIPBusiness calling over your internet connection, on the devices your team already carries.
- Cloud CommunicationVoice, numbers and routing run as a managed service instead of equipment you maintain.
- Wholesale VoiceTermination and origination at carrier scale, for operators and resellers moving real volume.
FAQ
Common questions
Anything specific to your destinations, numbers or endpoints is confirmed directly rather than answered generically.
Will my existing PBX work with it?
Most SIP-capable systems will. Tell us the platform and version and we will confirm compatibility and what configuration it needs before anything is provisioned.
How many channels do we need?
It depends on concurrent calls at your busiest point, not on headcount. If you have historic call data we can size it from that; if not, we start from a sensible figure and adjust.
What happens if our site goes offline?
Inbound calls follow a failover path you define in advance — a second site, a mobile group, or an out-of-hours destination. It is configured up front, not arranged during an outage.
Next step
Ready to set up sip trunking?
Tell us how your calls work today and where they need to go. We'll map the route with you before anything is configured.