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Programmable Unified Communications | SignalWire

Programmable Unified
Communications (PUC)

Escape the CPaaST. Build What’s Next.

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A new way to build

Programmable Unified Communications (PUC) is a new category of cloud communications that replaces the fragmented tools of CPaaS, UCaaS, and CCaaS with a unified, programmable model. It gives developers a new way to build, not by stitching together APIs or buying rigid software, but by using modular, cloud-native resources.

Developers get full programmatic control while teams get unified workflows across voice, video, messaging, and AI. PUC lets you build, scale, and own your communications without reinventing the infrastructure or duct-taping disconnected services together.

Unified everything

Voice, video, messaging, SIP, webhooks, AI: PUC brings them under one system. Fewer vendors, fewer dashboards, fewer ways things can break.

Elastic scaling

PUC is cloud-native. You don’t need to forecast traffic spikes or provision servers. Whether it’s 10 calls or 10,000, the same logic applies.

Full customization

Build exactly what you need - voice menus, AI IVRs, video rooms, call centers - without managing SIP servers or writing every line from scratch.

Call Fabric: SignalWire’s PUC implementation

Before PUC, cloud communications meant compromise. You could either build it all yourself with APIs (CPaaS), lock yourself into an inflexible suite (UCaaS), or spend big on specialized customer tools (CCaaS).

SignalWire offers a next-generation cloud communications platform that replaces legacy infrastructure with a fully programmable, composable system designed for ultra-low latency and high scalability. Route calls, manage SIP endpoints, build IVRs, and scale automatically. All from your code.

Call Fabric is SignalWire’s full implementation of PUC, abstracting the complexity of a telco stack into programmable Resources. Resources do it all, from using scripts to define call flows and automation to connecting AI agents to your existing FreeSWITCH. Everything is programmable, assignable, and callable, just like web APIs.

SWML: A unified language for voice and AI automation

Build serverless AI IVRs

Add AI, advanced TTS, recording and more to IVRs

Route calls based on real-time data

Use AI to collect data and summarize for live agents

Collect PCI-compliant payments

Safely collect payments with SignalWire's compliant architecture

Translate and transcribe live calls

Translate real-time audio conversations between multiple languages

Connect every protocol

Route calls across protocols, from browser to trunk or PSTN to softphone

The modern, programmable dialplan. No telephony servers required.

SignalWire Markup Language (SWML) is a declarative JSON/YAML framework that combines:

→ XML dialplan structure

→ Real-time call control

→ CPaaS-like cloud execution

→ Built-in methods for ai, gather, connect, live_transcribe, live_translate and more

Git the code
Git the code
Git the code
Git the code

The CPaaST called… They want their telephony stack back.


Your product (and end users) shouldn't be at the mercy of your CPaaS's capabilities.

Signs you're in the CPaaST:
  • Your roadmap is tied to what your vendor supports, not innovation or market changes.
  • You turn customers away if they need unique features like AI, advanced call flows, or custom CRM integration.
  • Your contact center offers the exact same features as your competitors.
  • You have 1-3 seconds of added latency, especially during peak times.
  • You have no control over your call routing, limiting your ability to optimize call quality, redundancy, and cost.
  • Customers can't bring their own communication tools or carriers.
You could build from scratch, but...
  • Infrastructure costs and efforts, like setting up data centers, SIP trunks, PSTN interconnects, and WebRTC servers, are too much for your operations.
  • You don't have the resources to negotiate with hundreds of telecom carriers worldwide to support international calling, messaging, and compliance.
  • Telecom networks require continuous monitoring, failover planning, and software updates.
  • You're unable to handle multiple regulatory requirements across multiple countries (GDPR, HIPAA, PCI-DSS, etc…)
  • Vultik
  • Samsung
  • Audi
  • Phoenix Children's
  • Growthzilla
  • Prompt.io
  • Textline
  • Filevine
  • McFarland Clinic
  • Replicant

Programmable Unified Communications FAQ

What is PUC?

PUC is a new cloud communications model pioneered by SignalWire that combines the programmability of CPaaS with the unified features of UCaaS and CCaaS. It enables developers to build and control voice, video, messaging, and AI applications with full flexibility and scalability.

How is PUC different from CPaaS, UCaaS, and CCaaS?

CPaaS gives you APIs to build features but not a unified platform. UCaaS is a prebuilt internal communication suite with limited customization. CCaaS is designed for customer support, often with fixed workflows.

PUC blends all three: unified, programmable, and open for custom development.

What features should I look for in a PUC solution?

PUC as a category is defined by its modular, programmable architecture that combines the best of CPaaS, UCaaS, and CCaaS, but with more developer control. Key features will include declarative call control; programmable primitives like SIP endpoints, AI agents, and conferencing; REST + Real-time APIs; scalable, serverless infrastructure.

How does SignalWire fit into the PUC space?

Call Fabric is SignalWire’s implementation of PUC. It provides a set of programmable building blocks called Resources, which include AI agents, rooms, call flow scripts, and subscribers that can be deployed, assigned addresses, called, and used in real-time applications via API or visual UI. We created PUC after decades of seeing developers forced to choose between duct-taping APIs together or getting locked into rigid telecom software. It’s born from the limitations we lived through building FreeSWITCH, and the belief that communications should be programmable by design.

Who should use PUC?

  • Developers who want full control without managing telephony infrastructure
  • Businesses needing customized voice and video workflows
  • Teams looking to combine customer service and internal comms into one system
  • Startups building new communication products on a modern stack

What kind of applications can you build with PUC?

  • AI-powered IVRs
  • Hybrid support systems
  • Scalable video conferencing
  • Internal communication suites
  • Global virtual call centers

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