A modern, open-source SIP proxy, B2BUA, and IMS engine — built from scratch as a ground-up alternative to Kamailio and OpenSIPS.
SIPhon is our open-source contribution to the telecom community, and the foundation our carrier-grade IMS is built on. A Rust core for performance and memory safety, with Python scripting for business logic — hot-reloaded and decorator-based, with no proprietary config languages.
Most voice platforms are assembled on top of someone else’s core. Ours isn’t. SIPhon is the layer underneath our IMS — and it’s ours, open-source and fully in our control. The carrier-grade IMS we build on top is proprietary, but the foundation is open for anyone to inspect. That means no black boxes in your voice core, and an engineering standard you can verify for yourself.
SIPhon is a complete, standards-based SIP stack — proxy, B2BUA, and registrar — with stateful forking, presence, and GRUU support across every transport (UDP, TCP, TLS, WebSocket, and SCTP). On top of that it provides the core IMS functions for carrier-grade voice (P-CSCF, I-CSCF, and S-CSCF), along with Diameter integration, 3GPP authentication, media anchoring, call recording, and lawful intercept. It’s open-source, MIT-licensed, and extensively tested.
We believe the core SIP/IMS layer should be transparent and auditable. Open-sourcing SIPhon lets operators inspect exactly what runs in their network, builds trust, and keeps us honest about our engineering standards.
SIPhon is MIT-licensed — use it, fork it, contribute. If you need commercial support, managed deployments, or custom development on top of SIPhon, that’s what we do.
Carrier-grade telecom infrastructure built for performance. From mobile core networks to voice platforms — delivering your telecom service in real time.
