Fonoster

Best Self Hosted Alternatives to Fonoster

A curated collection of the 1 best self hosted alternatives to Fonoster.

Cloud communications platform offering programmable VoIP/SIP, PBX features, call routing, SIP trunking and APIs/SDKs to build voice-calling applications and telephony workflows, including signaling, media handling, and integrations for developers and businesses.

Alternatives List

#1
Routr

Routr

Routr is a programmable SIP server (proxy/registrar/location) for building scalable VoIP infrastructure with APIs, multi-tenancy, and Kubernetes-ready deployment.

Routr screenshot

Routr is a lightweight, cloud-ready SIP server that acts as a proxy, registrar, and location service for modern VoIP networks. It is designed to be programmable and scalable, making it suitable for carriers, communication service providers, and integrators.

Key Features

  • Core SIP server functions: proxy, registrar, and location service
  • Programmable routing with configurable strategies (intra-domain, ingress/egress, peer egress)
  • Load balancing and session affinity for upstream media servers (for example Asterisk or FreeSWITCH)
  • Multi-tenant and multi-domain support with domain-level access control lists
  • Multiple transports: UDP, TCP, TLS, WS, and WSS
  • Pluggable processors and middleware for extending routing and cross-cutting concerns
  • Server management via APIs and tooling (CLI and gRPC management API)
  • Flexible data sources, including Redis-backed location service and PostgreSQL

Use Cases

  • Run a scalable SIP edge/proxy in front of one or more PBXs or media servers
  • Build programmable SIP routing for multi-tenant VoIP platforms
  • Deploy carrier-grade SIP infrastructure on Docker or Kubernetes

Routr provides a modern approach to SIP infrastructure by combining core SIP capabilities with APIs, extensibility, and cloud-native deployment patterns. It is a strong fit when you need a configurable SIP control plane that can integrate cleanly into automation and platform workflows.

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Why choose an open source alternative?

  • Data ownership: Keep your data on your own servers
  • No vendor lock-in: Freedom to switch or modify at any time
  • Cost savings: Reduce or eliminate subscription fees
  • Transparency: Audit the code and know exactly what's running