Build hosted IPPBX and cloud phone platforms with SIP, WebRTC, IVR, ACD, DIDs, recording, billing, white-label, CRM, AI voice, APIs, provisioning, monitoring and horizontal scale.
Direct answer: A Cloud PBX is SIP extensions, IVR, trunks and recording you can snapshot and operate, not a UCaaS seat you cannot inspect. UnifiedPBX.in builds the platform; it is not a public PBX login.
What operators buy here: multi-tenant provisioning and reseller admin, white-label portals, per-tenant billing hooks, carrier/SIP onboarding, recording retention you control, and runbooks for support, not per-seat resale of a black box. India and worldwide delivery. Live: Asterisk 22 IP PBX demo · Case: UnifiedPBX on Asterisk 22 · Multi-tenant PBX hub · Hire FreeSWITCH.
Who this is for. Offices and MSPs replacing hardware IPPBX or a locked UCaaS; startups and SaaS teams that need calling they can extend; operators moving toward hosted voice.
What you get. Hosted extensions, IVR, recording, failover and a trunk diagram, not a consumer app with a company name. Growth path to multi-tenant if you do not paint yourselves into a corner.
2026 context. “Cloud PBX” still means three products: a suite seat, a FusionPBX domain, or a vertical you own. This page is the third, with an option to operate the second. Recording locality and CLI reputation are designed up front. Failover is a second trunk and a tested dialplan, not a marketing noun.
Searches this page answers: hosted IPPBX software · best cloud IPPBX · cloud IP PBX · cloud-hosted IP PBX · cloud PBX development · FreeSWITCH / Asterisk cloud PBX · multi-tenant VoIP · cloud PBX vs UCaaS vs CCaaS
A Cloud PBX is a business telephone system hosted on cloud or internet-connected infrastructure instead of a traditional on-premises PBX appliance. Users make and receive business calls through SIP phones, softphones, WebRTC browsers or mobile applications while call routing, IVR, queues, extensions, recordings and administration are managed centrally.
Traditional PBX
Office
│
├── PBX Hardware
├── Phones
├── Local Network
└── PSTN / SIPCloud PBX
Users ─────┐
Branches ──┤
Mobile ────┤
WebRTC ────┤
SIP Phones ┘
│
▼
Internet
│
▼
┌───────────────┐
│ Cloud PBX │
│ SIP / IVR │
│ Queues │
│ Routing / CDR │
│ Recording │
│ APIs │
└───────┬───────┘
│
▼
SIP / PSTNA cloud PBX is SIP extensions + business hours + trunks + recordings on infrastructure you can snapshot. UnifiedPBX.in builds that for companies leaving a hardware box, and for operators who want to host customers without becoming a Zoom reseller.
Client (SIP / WebRTC / Mobile)
│
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Access (TLS SIP · WSS · VPN)
│
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PBX VM / cluster (FreeSWITCH · Asterisk · FusionPBX)
│
┌────┼────┐
▼ ▼ ▼
Carriers IVR/Voicemail Admin portal
Local+backup Hours/prompts Users · CDR · devicesHigh availability is two signaling paths and a tested failover, not a checkbox on a VM size. Related: hosted PBX, VoIP development.
Business numbers, extensions, IVR, call forwarding, ring groups, voicemail, recording and business-hours routing, without maintaining traditional PBX hardware.
Employees work from home, office, branches, co-working spaces or mobile devices while keeping the same business identity and number.
Cloud PBX
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┌────────────┼────────────┐
▼ ▼ ▼
Delhi Mumbai Bangalore
Office Office Office
│ │ │
Users Users UsersLong-tail intent: cloud PBX for multiple locations, branch offices and multi-site phone systems.
Business telephony without a large physical telephony plant, with a path to productize later.
High availability, SIP trunk redundancy, multiple regions, centralized management, SSO, RBAC, monitoring, disaster recovery and API integration.
Replace legacy PBX with modern cloud calling you can inspect and extend.
Add managed business voice to your service portfolio, then grow into multi-tenant.
Build your own hosted voice platform rather than only reselling seats.
Embed calling into the product, see VoIP / TPaaS.
Queues, agents, recordings and analytics, CCaaS.
Connect distributed offices, or ship a cloud communications product.
Incoming Call → Business Number → IVR / Auto Attendant
→ Department → Ring Group → Employee Cloud PBX
│
┌────────────┼────────────┐
▼ ▼ ▼
Softphone WebRTC Mobile
└────────────┼────────────┘
▼
Business NumberCustomer → DID → IVR → Queue → Agent → CRM → Call Record / CDRDeeper contact-center designs: CCaaS, AI call center.
CRM → Click-to-Call → PBX → Customer → CDR → CRM activity, where telephony meets CRM/ERP.
SIP extensions · SIP trunks · DIDs · inbound/outbound routing · call forwarding · caller ID · ring / hunt groups · voicemail
IVR · queues · parking · transfer · pickup · business hours · holiday and time-based routing · failover routing
ACD · agent states · queue management · supervisor monitoring · recording · CDR · reporting · campaigns
SIP phones · desktop softphones · WebRTC · mobile apps · PWA
REST APIs · webhooks · CRM/ERP integration · authentication · RBAC · multi-tenancy · billing · provisioning
USERS
│
┌────────────────┼────────────────┐
▼ ▼ ▼
SIP Phones WebRTC Mobile
└────────────────┼────────────────┘
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┌──────────────┐
│ Load Balancer│
└──────┬───────┘
▼
┌──────────────┐
│ API / Control│
│ Plane │
└──────┬───────┘
│
┌────────────┼────────────┐
▼ ▼ ▼
PBX Engine API Layer Auth / RBAC
FreeSWITCH/Asterisk NestJS/FastAPI Identity
│
┌───────┼────────┐
▼ ▼ ▼
SIP RTP WebRTC
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SIP Trunks / Carriers → PSTN
Application Services
CRM / ERP · Billing · Analytics
│
PostgreSQL / Redis / Object StorageThe PBX engine handles SIP signaling, call routing, media processing, dialplans, extensions, IVR, queues and other telephony functions. The application layer manages provisioning, tenants, users, business rules, billing and integrations.
Application Layer → API / Control → PBX Configuration
→ FreeSWITCH / Asterisk → SIP / RTP / WebRTCServices: FreeSWITCH · Asterisk · FusionPBX.
Production designs cover PJSIP/Sofia profiles, digest vs IP auth, OPTIONS keepalives, codec offers, RTP pinholes and carrier test matrices. REGISTER alone does not prove calls work, see SIP trunk registered but no calls. Indian PSU and PRI-over-SIP profiles are a common real-world case.
Use CPaaS (Twilio/Telnyx) when volume is low and speed matters. Own SIP when margin, recording locality, custom routing or multi-tenant resale is the product. Hybrid designs are normal in 2026.
Browser → WebRTC → WebRTC Gateway / SIP → PBX → SIP Trunk → PSTNCapabilities can include browser calling, softphone UI, presence, hold/transfer/mute, call history and click-to-call. Related: WebRTC softphone, WebRTC development.
Employees should not need to be physically connected to the office PBX.
Cloud PBX
│
┌─────────┼─────────┐
▼ ▼ ▼
SIP WebRTC Mobile App → REST API
PhonePossible stacks: React Native, Ionic, Capacitor, PWA, SIP/WebRTC, push notifications and backend APIs, mobile clients.
CRM → Click to Call → PBX API → SIP Call → Customer
Call → CDR → Recording → Transcript → Summary → CRM ActivityIntegrations can include Salesforce, HubSpot, Zoho, custom CRM/ERP, helpdesk, calendar, WhatsApp and SMS. Related: custom CRM/ERP, n8n automation.
Caller → Cloud PBX → AI Voice Runtime
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┌────┼────┐
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STT LLM TTS
│
Business Tools
CRM · Calendar · ERP · Ticketing · KnowledgeUse cases: AI receptionist, AI IVR, lead qualification, appointment booking, customer support, call summarization, automated outbound, agent assist and intelligent routing. See AI voice and AI voice development.
| Capability | Traditional on-prem PBX | Cloud PBX |
|---|---|---|
| Infrastructure | Customer premises | Cloud / hosted |
| Remote users | More complex | Native architectural fit |
| Multi-location | Requires networking | Internet-based architecture |
| Scaling | Hardware / config | Software / infrastructure |
| Updates | Customer-managed | Centralized |
| WebRTC / mobile | Additional architecture | Can be integrated |
| API / AI | Depends on PBX | API-first paths possible |
| Monitoring | Local | Centralized observability |
Cloud is not universally “better.” The right choice depends on residency, latency, existing plant and compliance.
A hosted PBX generally means a PBX service operated by a provider for customers. A cloud PBX describes deployment on cloud or internet-accessible infrastructure. The terms overlap heavily in commercial usage.
UnifiedPBX designs and develops the underlying architecture rather than restricting the offering to a fixed hosted-seat product, targeting cloud PBX development, custom hosted PBX and build-your-own cloud PBX intent. Related: hosted PBX solution.
Cloud PBX → business phone system (extensions, IVR, trunks, recording)
UCaaS → unified communications (voice + meetings + messaging + presence)
CCaaS → contact center (queues, ACD, campaigns, agents, QA, AI workers)| Need | Start with | When to grow |
|---|---|---|
| Office dial tone, DIDs, IVR, recording | Cloud / hosted PBX | Multi-site, WebRTC, CRM click-to-call |
| Meetings, chat, softphone as the workplace | UCaaS layer on PBX/SIP | Presence, messaging, desktop clients |
| Queues, campaigns, supervisors, AI agents | Custom CCaaS | Same event schema for AI + humans |
| Sell voice to many companies | Multi-tenant PBX | Billing, white-label, isolation |
Do not buy a CCaaS suite when you only need hosted IPPBX, and do not expect a Cloud PBX seat product to become a contact-center platform without queues, agent desktop and CRM truth. Architecture article: CCaaS/UCaaS layers.
Single-tenant or per-customer VPC early; multi-tenant when ops cost and onboarding volume demand shared media with strict isolation.
Infrastructure: Docker, Kubernetes where appropriate, Nginx, load balancing, PostgreSQL, Redis, object storage, message queues, monitoring, centralized logging, automated deployment, backups and disaster recovery.
Voice-specific: SIP signaling, RTP, NAT, firewall, SBC, TLS, SRTP, codecs, RTP port management, SIP trunk redundancy and carrier failover. Related ops: cloud & DevOps, production rescue.
SIP Traffic
│
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Load Balancer
/ \
▼ ▼
PBX Node 1 PBX Node 2
└─────┬──────┘
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Shared Data
PostgreSQL · Redis · StorageActual HA design depends on shared state, distributed media, database HA, geographic redundancy or active/standby behavior, not a single “HA checkbox.”
SIP authentication · TLS · SRTP · firewall · Fail2ban · IP restrictions · rate limiting · RBAC · API authentication · secrets management · tenant isolation · audit logging · recording access controls · encryption · backup security.
Extensions, ring groups, parking, transfer, conference.
IVR, queues, announcements, holiday routing.
On-demand or always-on, with access roles.
Provisioning or a supported softphone list, pick one and document it.
Someone who is not the founder can add a user.
The same core can become multi-tenant later if we do not paint ourselves in.
| Layer | Technologies |
|---|---|
| PBX | FreeSWITCH, Asterisk, FusionPBX |
| SIP / media | PJSIP, Sofia-SIP, RTP, SRTP, WebRTC |
| Backend | NestJS, Node.js, FastAPI, Laravel, Go |
| Frontend | React, Next.js, Vue |
| Data | PostgreSQL, Redis, S3-compatible storage |
| Infra | Docker, Kubernetes, Nginx, AWS/Azure/GCP |
| Observability | Prometheus, Grafana, OpenTelemetry |
| AI / automation | OpenAI, Claude, Gemini, Azure/AWS AI, n8n |
Direct answer blocks for search and AI summaries, aligned with visible content on this page.
Send current architecture, call volume, carriers, locations and the workflow you need to automate or productize. Discovery can start from a broken PBX or a blank product brief.
Discuss Your Project hello@unifiedpbx.inCloud phone system → multi-tenant / white-label → WebRTC & mobile → CCaaS → AI voice → CRM.
A practical technical discussion focused on SIP, media, clients, AI and the delivery path, not a generic sales deck.