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Reliable, scalable SIP trunk services designed for organisations that depend on voice as a critical business channel.
Our SIP trunking service provides enterprise-grade voice connectivity through managed carrier relationships. We handle the full provisioning lifecycle from initial capacity planning through to live deployment, including DDI allocation, number porting, and integration with your existing PBX or contact centre platform. Each deployment is configured with automatic failover routing across multiple carrier paths, so that inbound and outbound calls continue uninterrupted in the event of a circuit or carrier issue.
We include fraud monitoring as standard across all SIP trunk deployments. Our systems analyse call patterns in real time and apply automated controls to prevent toll fraud, international revenue share fraud, and other common attack vectors. Clients receive alerts and can set custom thresholds that match their expected traffic profiles.
Call capacity is managed proactively. We monitor concurrent call volumes against provisioned capacity and recommend adjustments before limits are reached. This ensures that peak periods, campaign launches, and seasonal volume increases do not result in blocked or failed calls. Detailed call records are available through our reporting portal, giving full visibility of traffic volumes, call durations, and routing outcomes.
SIP trunking is a way of delivering telephone calls over an internet or private data connection instead of traditional ISDN phone lines. A SIP (Session Initiation Protocol) trunk connects your phone system — an on-premise PBX or a cloud contact-centre platform — to the public telephone network through a provider, carrying multiple simultaneous calls (channels) over a single connection. Because it is software-defined, capacity can be scaled up or down without installing physical lines.
When someone calls your business, the call is routed over the SIP trunk from the public network to your phone system, and outbound calls travel the same path in reverse. Each trunk carries a defined number of channels — one channel per simultaneous call — and calls are set up and cleared using the SIP signalling protocol. Voice is carried as data packets, so quality depends on sufficient bandwidth and properly configured quality-of-service (QoS) on your network, which we assess and monitor as part of the service.
The UK’s traditional analogue PSTN and ISDN network is being progressively withdrawn ahead of the national ‘big switch-off’, which Openreach has targeted for the end of January 2027. Any organisation still running voice over ISDN needs a migration plan before then. SIP trunking is the direct, like-for-like replacement: it keeps your existing numbers and phone system where possible while moving the underlying connectivity to IP. Migrating early avoids a last-minute rush and unlocks the cost and flexibility benefits sooner.
SIP trunking is usually priced per channel (each channel carries one concurrent call) plus call charges, and is typically significantly cheaper than equivalent ISDN lines and line rental. The right number of channels depends on your peak concurrent call volume, so we provide a tailored quote based on your capacity and number requirements rather than a fixed list price.
One channel supports one simultaneous call. As a rule of thumb, size your channels to your busiest-hour concurrent call volume rather than your total number of users, because not everyone is on a call at the same time. We help model this from your call data during provisioning.
Yes. We port your existing geographic and non-geographic numbers to the new SIP service so customers reach you on the same numbers, and we manage the porting process end to end.
Our SIP trunks are configured with automatic failover routing across multiple carrier paths, and calls can be diverted to alternative destinations such as mobiles or another site if your primary connection is unavailable, so you don't miss calls.
Our voice engineering team can assess your current connectivity and recommend a SIP trunking configuration that meets your capacity, resilience, and compliance needs.
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