Moving past ISDN isn’t just about avoiding legacy shutdowns. Today’s top SIP trunk providers and cloud voice enablers are more than just connectivity partners. They’re helping enterprises unlock security, agility, versatility, and new opportunities to grow and thrive in a changing landscape.
The cloud is the future of scalable communications, and the best vendors can help you get there without unnecessary headaches. The question is, who can you really trust? We’ve created this insider guide to the best SIP trunk providers and cloud voice pioneers in the market.
Based on our own comprehensive cloud voice marketplace, this list will help you pinpoint the ideal copilot for your journey into the next era of voice connectivity.
We’re keeping things real, focused on what matters to enterprise decision-makers: reliability, compliance, hybrid work-fit, and total cost of ownership.
The Top SIP Trunk Providers for Cloud Voice
The Top SIP Trunk Providers and Cloud Voice Leaders
Everyone, from industry analysts, to enterprise leaders, knows the future of voice is in the cloud. By 2032, this market will be worth more than $42.7 billion. The biggest challenge is figuring out how to get there, as painlessly as possible.
We’ve pulled together a carefully curated list of top SIP trunk providers and cloud voice vendors that are helping enterprises around the world modernize their communications stack. Some of these companies have been delivering voice infrastructure for decades. Others are rising fast by building smart, flexible platforms that plug into your UC environment, without the usual complexity.
They’re all here to make it easier to leave legacy systems behind, and scale voice into the future.
AT&T
A well-known provider of telecommunications solutions, AT&T offers a range of services and tools to businesses looking to leverage the benefits of the cloud. AT&T’s portfolio includes everything from a comprehensive cloud-based platform with API access to existing UC solutions, as well as VOIP services, SIP Trunking, and more.
AT&T’s IP Flexible Reach also gives enterprises a way to modernize without overhauling telecom hardware. If you’re running a legacy PBX or want to hook directly into Microsoft Teams via Direct Routing, this service lets you combine voice and data on the same MPLS circuit. That means far fewer dropped calls and better quality than you’d get over public internet
AT&T also launched Business Voice, which transitions analog devices like fax machines, alarms, and elevators to IP while keeping numbers and compliance intact. It’s a smart hedge if you’re ditching copper but still rely on legacy endpoints.
BT
BT is another of the top SIP trunk providers with a huge presence. The company’s Global SIP solution offers a smooth route into post-ISDN voice transformation, ideal if your footprint stretches across Europe and beyond. It offers SIP trunking with encrypted signalling, global number support, and a unified dashboard for fast provisioning and usage tracking.
In early 2025, BT rolled out Global Fabric, a cloud-ready private network spanning over 45 points-of-presence and hundreds of data centers worldwide. That matters because your voice and video traffic can stay off the public internet, reducing jitter and boosting quality for Teams Rooms or Zoom Rooms.
BT has also refreshed its meeting room device offerings by bundling deployment, device management, and user training. They’ve partnered with Cisco, Poly, Logitech, Microsoft, and Neat to support full collaboration suite rollouts.
Nuwave
Nuwave is a hidden gem among the top SIP trunk providers and cloud voice leaders if your’e trying to streamline communications across multiple platforms, particularly Microsoft Teams, Zoom Phone, and Webex Calling. Their iPILOT platform automates everything from provisioning to device management, so customers can flip on calling in minutes.
They also support both Direct Routing and Operator Connect, making them flexible enough to fit into any Teams migration plan. A standout feature is their multi-UC automation, which means you don’t need separate vendor portals or messy integrations. Add-ons like SMS, call recording, and even cloud fax are available through an intuitive marketplace, letting you build exactly the calling stack you need.
For organizations with global users, their SYNTHESIS network supports multi-country numbering and trunk migrations in about 30 days.
Verizon
Verizon’s Enterprise SIP solution wraps a familiar story in a bigger infrastructure. If your enterprise has a sprawling MPLS or SD‑WAN voice overlay, Verizon simplifies trunk management and rolling deployments across thousands of sites.
The shift to the new Verizon Enterprise Center portal has given admins better reporting and a modular view of voice, contact center, and security services. Verizon excels in resilience and integration too. Their SIP trunks support automatic failover, dynamic bandwidth balancing, and TLS/SRTP security protections . Plus, they connect cleanly into Cisco, Avaya, and Microsoft Teams PBXs, reducing rip-and-replace pain. V
Verizon also bundles Webex Audio Conferencing with their UC stack and encourages upgrades to Hosted PBX or hybrid contact center over time .
Pure IP
Pure IP is built for enterprises who want global voice coverage without complexity. Their cloud voice service supports Microsoft Teams (Operator Connect and Direct Routing), Webex Calling, and Zoom Phone from a single managed platform. They also introduced Mobile Connect for Microsoft Teams, which lets frontline workers use native mobile dialers with corporate Teams numbers via eSIM.
One clever add-on is SIP Connect, which bridges analogue and on-prem devices, fax, intercom, elevators and more to your cloud. Their portal handles onboarding, configuration, porting, and APIs, with 24/7 support and global voice coverage across 80+ countries. IT teams praise their high NPS and reliable routing .
If your enterprise is juggling legacy endpoints, frontline mobile staff, and hybrid collaboration, Pure IP ties it all together in one smart voice strategy.
Gamma
Gamma Telecom is a full-service communications vendor, offering a range of tools from comprehensive SaaS services like line rental to fraud management and security tools. They’re one of the top SIP trunk providers in the UK, with around one in three businesses running their network.
The Gamma SIP Trunks service plugs your PBX (on-site or in their collocated hubs) directly into their cloud, supporting features like call resiliency, cloud-based inbound routing, and full PSTN breakout. With 99.99% voice availability, it’s clearly built for reliability.
They’ve also tightened integration with Microsoft Teams offering Direct Routing services. Enterprises appreciate how Gamma handles voice failover, if a branch goes offline traffic automatically reroutes to alternate office or to mobile. Plus, their call management portal offers IVR, queueing, even call recording, all manageable through one dashboard.
CallTower
CallTower’s CT SIP trunking throws a global, managed voice layer over wherever your UC and PBX strategy lands. Whether it’s Teams, Webex, Zoom, or a private cloud PBX, they fold it into a single SIP overlap that travels on their MPLS or public internet backbone.
They’ve given their Connect portal a serious makeover. So when admins log in, they get real-time trunk usage, failover alerts, E‑911 monitoring, and spam-blocking without digging through CLI logs . CallTower also added burstable capacity for seasonal or campaign-driven spikes, outbound SMS, and CRM-aligned routing through “CT Unite” integrations for Salesforce and Microsoft Dynamics .
CallTower’s global footprint spans 15 data centers and covers 80+ countries via redundant voice paths, so international performance isn’t an afterthought.
NTT Global Networks
Offering a range of simple communication tools for business leaders, NTT addresses numerous enterprise needs. The brand’s portfolio includes access to network consulting services, a global IP network, and even private 5G solutions.
As one of the top SIP trunk providers, NTT offers end-to-end voice infrastructure, from trunking all the way to room endpoints, including standard and conference room handsets, with flexible deployment models. Plus, NTT offers call plans across 39 countries, with data centres located around the globe. NTT also promises a highly resilient wholly-owned network with ultra-fast connectivity speeds and built-in tools for security.
The real differentiator lately has been their push into AI-powered network management. They’ve woven AI into their software-defined infrastructure, melding voice, data, security, and analytics into one unified platform .
Deutsche Telekom
In Germany and across Europe, Deutsche Telekom’s CompanyFlex SIP Trunk is a go-to solution for modular, scale-up voice. It allows businesses to add parallel call paths, SIP gateways, and bandwidth in a plug-and-play way, keeping migrations clean and predictable.
The brand’s open Telekom cloud allows users to connect their own devices to the company’s Telekom infrastructure without compromising on privacy and security. Functions include everything from mobile device integration to audio conferencing, presence information, and intelligent call routing.
At MWC 2025 they showcased a new AI Phone, featuring a virtual assistant for admin tasks, booking conference rooms, handling translations, even drafting emails, highlighting their AI-first direction. If you’re rolling out SIP trunks across a European network, or want smart endpoint management woven into your voice platform, Telekom brings modular workflows with a side of AI smarts.
Intrado
Intrado has carved out a niche by doing one thing exceptionally well: emergency‑ready SIP trunking. Their NG911 Core Services ensure seamless routing, caller-location precision, and interoperability across legacy SIP, ESInet, and i3 architectures.
Their recent launch of NG Nexus takes this further, automatically assessing PSAP readiness and tailoring 911 call routing in real time, stripping the compliance burden from service providers. They’re even doing clever work around translating extension-based dialing into routable DID numbers via XBind, to ensure callbacks hit the right endpoint.
Intrado also has its own dedicated Microsoft Teams voice solution, as well as resources and value-added support for direct routing and Operator Connect.
Orange Business Services
Orange’s Business Talk SIP Trunks have matured into an enterprise-grade voice service built for simplicity. Covering 142 countries for inter-office calling and delivering PSTN connectivity in over 28 countries, Orange has leaned hard into Direct Routing for Microsoft Teams.
They’ve also invested in real-time analytics and contact center control, managing routing, performance metrics, and queueing through a single regional dashboard with 99.99% uptime and bilingual support.
At Viva Technology 2025, they showed off a secure quantum-layered network for encrypted video calls, and teased prototypes for generative AI over private 5G. That tells you they aren’t just delivering voice, they’re building the secure, future-ready infrastructure that sits beneath it.
Tata Communications
Facilitating borderless growth with enterprise voice solutions, Tata Communications offers a range of managed VoIP services and SIP solutions. The company supports business conversations through a robust, global network enabled via partnerships with tier-1 carriers.
One of the things that makes this company one of the top SIP trunk providers is its focus on automation. You can spin up international DIDs, toll-free numbers, or local service numbers via API, with minimal hassle. They also tout 40–60% cost savings, especially for companies with high international call volumes.
Tata’s global trunking supports intelligent call queuing and CRM-linked routing, making it a natural fit for distributed contact centers and global sales teams, too.
BICS
Working with MVNOs, network providers, and mobile operators, BICS provides various communication solutions for the cloud-focused landscape. The brand can deliver cloud numbers instantly, alongside Bring your Own Carrier services for communication strategies. For Microsoft Teams users, BICS also supports Operator Connect and Direct Routing.
Their SIP trunking lets you manage voice and numbers through APIs, offering fast provisioning of local, national, toll-free, and even mobile numbers in 130+ countries. BICS also wraps voice and messaging together. For instance, if you want SMS or alerts tied to voice calls, it’s a built-in feature. Analytics are also baked in for in-depth insights.
If your organization is chasing international scale and wants voice and messaging, handled as code, BICS delivers voice without borders.
IntelePeer
IntelePeer has built a strong reputation for combining voice infrastructure with developer-friendly flexibility. Their CoreCloud SIP Trunking service is viewable and manageable entirely through a self-service portal, where you can order trunks, set up DIDs, monitor usage, and pull granular call reports.
They support all major PBX and SBC vendors, including Cisco, Avaya, Microsoft, so you don’t need to rip and replace your existing setup. Like some other top SIP trunk providers, they’re also bringing AI into play: IntelePeer’s Conversational AI features can help surface call trends and even automate simple customer interactions.
Plus, IntelePeer also allows users to leverage tools like mobile messaging, smart multichannel communications and spam protection for internal and external calls.
DSTNY
DSTNY is Europe’s fast-growing, service-provider-focused voice platform, offering SIP trunking integrated directly with Microsoft Teams via their “Call2Teams” product. So if your IT team wants to keep call flows inside Teams while still using carrier-grade trunks, DSTNY makes that easy, even for multi-tenant or service-provider scenarios.
They operate across seven European markets, serving over 3 million users with flexible bundles and managed voice alongside mobile and UC tools. Their system supports unified analytics, mobility, and carrier-grade compliance, all in a pane of glass made for service providers and enterprises who want to stay agile.
Service packages offer customisation flexibility for unique business needs, as well as high levels of security and a 99.9% uptime guarantee. For service providers and partners, DSTNY also has its own Operator Connect accelerator service.
Enreach
Enreach focuses on merging intelligent SIP trunking with on-switch improvements and user experience. Their service enhances your PBX with rules-based call handling, voicemail, call recording, and even AI-driven responses all the way from the trunk to the desktop.
As one of the top SIP trunk providers, they cater to enterprises needing easy scalability. You can add more seats as your org grows, with no hardware changes. Enreach also offers global SIP trunking options, making it easier to manage inbound and outbound traffic as you expand internationally.
Plus, users can either leverage the full Enreach cloud PBX system or connect the technology available to their existing platforms, such as Microsoft Teams. There’s even the option to leverage contact centre tools for customer experience management.
Sinch
Sinch has turned SIP trunking into something they call Elastic SIP Trunking, and it fits perfectly within their broader communications cloud. With coverage across 95% of the U.S. and ranked among top North American providers, they promise scale you can turn on and off as needed.
What stands out is their unified dashboard, part of a platform that includes voice, SMS, email, and verification APIs. That lets tech teams spin up global voice numbers, configure SIP trunks, and add messaging or ID services without opening multiple portals .
For companies focusing on Microsoft Teams, Sinch offers Direct Routing and Operator Connect capabilities, alongside a host of integration options.
Six Degrees
Otherwise known as 6DG, Six Degrees is a cloud communications vendor with its own dedicated data and cloud services platform. The company supports brands in developing their communication infrastructure with SD-WAN capabilities. Business leaders can also take advantage of a Six Degrees Agile workspace for collaboration and customer service management.
In recent developments, Six Degrees launched managed cloud SBC-as-a-service, taking the pressure off enterprises to provision and maintain Session Border Controllers for Teams Direct Routing or hybrid PBX setups. That means quicker delivery and fewer network headaches. Their modular engineering model also supports burstable voice capacity during mergers, events, or seasonal surges, all packaged with SLAs on latency, jitter, and uptime.
If your enterprise is looking for a partner to deploy voice intelligently, blending carrier-grade SIP trunking with engineering and lifecycle management, Six Degrees offers a compelling model.
Telefónica Global Solutions
Recognized by industry analysts like Gartner, Telefónica Global Solutions offers access to wholesale solutions for solution providers and distributors in the communications space. The Cloud UC portfolio offered by the brand comes with global coverage and end-to-end support from systems integrators. Users can leverage a range of mobility licences, web portal management tools, and conferencing and collaboration packages from the same provider, with scalable and simple pricing structures.
As one of the top SIP trunk providers, Telefonica’s global service is deployable in 60+ countries, it supports direct routing, Teams integration, and hybrid PBX environments with unified governance and compliance. For 2025, their highlight is adaptive encryption at the network edge, with dynamic failover among Telefónica MPLS, SD‑WAN, and public internet links.
That ensures mission-critical call experience even if one link falters. Teams also get analytics via embedded dashboards and global numbering managed from a single pane of glass.
Telstra International
Telstra International offers wholesale voice solutions, cloud voice services, and VoIP technologies to a range of business leaders. The company provides access to a range of cloud calling services, with flexible phone numbers, voice lines, auto attendants and more.
Telstra’s SIP Connect is a robust, telco-grade SIP trunking network that integrates naturally with Teams, Zoom, Webex, and other platforms, complete with TLS/SRTP and global number support. Telstra also launched Network Access Control for SIP, which secures trunk origination at the router level, blocking unwanted traffic before it reaches your voice estate.
They’ve also expanded their public cloud peering footprint, meaning trunking sessions now experience lower latency when connecting into Azure, AWS, or Google Cloud environments.
Vodafone Business
Another of the better-known top SIP trunk providers on this list, Vodafone’s Voice Connect SIP trunking is tightly aligned with its global mobile backbone and SD-WAN services, offering a single pane for unified voice, data, and mobility.
Vodafone Business supports all kinds of companies in making the transition into the cloud. The Vodafone Business Interactive voice environment provides access to a complete call control system within the cloud, while Vodafone One Net Business connects landline and mobile communications.
Companies can also take advantage of integration with Managed Teams and Microsoft 365 environments. Vodafone bundles trunk provisioning, number management, encryption, and analytics via a self-service portal. In addition, they now offer Telepresence Voice Assist, a voice bot you can call in meeting rooms to initiate calls, adjust routing, and report network anomalies.
Bandwidth
Global communications provider Bandwidth delivers various cloud voice tools to business leaders, including voice APIs, calling solutions, and inbound and outbound calling apps. They run their own IP network with eight geo-redundant data centers and full PSTN replacement in over 38 countries, plus interconnects in 65+, covering 93% of the global economy.
The portal is built for IT teams. You can spin up or port numbers, monitor trunk usage, track outages and fraud attempts, all from one interface. Clients consistently talk about white-glove implementation and zero downtime during migrations. Plus, the SIP trunking services available from Bandwidth can be integrated with existing UCaaS and contact center platforms such as RingCentral, Genesys, and the Microsoft Teams platform.
If you’re migrating from old PRI systems or juggling hybrid voice platforms, Bandwidth’s elastic pricing, robust E‑911 compliance, and BYOC capability fit cleanly into large enterprise environments.
ULAP
ULAP aims to be more than just one of the top SIP trunk providers. This company positions itself as a global intelligent communications hub, with reach across 113 countries.
Their standout feature is the ULAP Smart Exchange, a cloud-native SIP backbone with global peering points, direct integration into platforms like Microsoft Teams, Zoom Phone, and NICE CXone, and built-in security layers to support compliance in regulated industries. ULAP has also earned recognition for their SBC-as-a-Service, helping enterprises simplify the edge while deploying Direct Routing or BYOC at scale.
What really clicks with global IT teams is how ULAP keeps things centralized. You get full visibility into trunk usage, smart failover routing, and global number provisioning from a single pane of glass.
Continuant
Continuant stands out by solving a problem many others avoid: how to move off legacy copper lines without losing mission-critical voice functions. Their Legacy Connect SIP-PSTN service is purpose-built for environments that still depend on analog devices like fax machines, alarm panels, elevators, and door systems.
Their platform acts as a digital bridge, mapping legacy traffic into modern SIP trunks with full E‑911 compliance, encryption, and redundancy. They support phased migration paths for hybrid environments and work closely with Cisco, Microsoft, and Avaya systems.
Continuant also stands out for ongoing support, with a managed service model that includes proactive issue resolution, round-the-clock monitoring, and PBX maintenance.
Fuse2
Otherwise known as Fuse2, Fuse is a Communications provider offering global voice to businesses around the world. Fuse 2 delivers VoIP call termination services, with an international network of data centres which can break out and redirect ingoing and outgoing calls.
They run their own carrier-grade voice network with full support for Direct Routing, plus global SIP interconnects that let you spin up or port numbers across 65+ countries in days. They’ve also doubled down on usability, rolling out a new customer portal that gives IT admins real-time access to call analytics, call recordings, number inventory, and even wallboard displays for contact centers.
Plus, Fuse has expanded integrations with Zoom and Cisco, and now offer automated provisioning through Azure AD and Okta for Teams users.
Ericsson
Ericsson’s SIP Trunking offering is built to support large-scale deployments of PBXs, UC platforms, and even contact centers. The core infrastructure focuses on regulatory compliance and global reach. It stitches stitching internal voice systems into public telecom networks with full services like number management, fallback routing, and control logic.
As one of the most reliable top SIP trunk providers on this list, Ericsson promises fast ROI through consolidation, with flexible, per-channel scaling. Their solution pairs especially well with enterprises already running other Ericsson network gear.
For enterprises, Ericsson promises to simplify technology consolidation, while ensuring businesses have the agility and flexibility to grow over time.
Embracing the Cloud with the Top SIP Trunk Providers
If you’ve made it this far, chances are you’re not just shopping around. You’re building a path to the cloud – a more flexible setup for your team, and greater agility. For that, you need the top SIP trunk providers, but you also need a plan.
There’s more to consider than just cloud connectivity. You might need to choose a new UCaaS platform, connect your cloud systems, or invest in cutting-edge endpoints. Fortunately, you don’t have to do it all alone. UC Today is here to help, as your dedicated guide to the world of unified communications, and digital transformation.
Here are some resources you can use to simplify your next steps:
- Dig deeper into the trends: Our latest market reports are packed with insights. Find out where vendors are heading, what IT buyers are prioritizing, and what to expect next.
- Learn from people facing the same challenges: Join our UC Community to connect with IT leaders, architects, and collaboration pros sharing practical advice and lessons from the field.
- See the tech in action: Check out upcoming events where you’ll meet vendors face-to-face, watch demos, and ask the kind of tough questions you can’t always get answered online.
- Take the guesswork out of buying: Our Ultimate UC Buyer’s Guide walks you through the entire process, from scoping requirements to rollout, so you can make a smart, confident decision.
The days of copper lines and siloed PBXs is over. This is the age of cloud agility, intelligent routing, and giving your teams a consistent, high-quality experience. Make sure you’re ready for the future of work, with a little help from UC Today.
