# Is the PortSIP PBX built on Asterisk, FreeSwitch?

No. **PortSIP PBX is not based on any open source PBX project**. It is a **commercial PBX platform fully developed by the PortSIP engineering team**.

At the protocol layer, PortSIP PBX is built on [reSIProcate](https://github.com/resiprocate/resiprocate), a mature and widely adopted open-source SIP stack written in C++. reSIProcate provides robust implementations of **SIP, ICE, TURN**, and related real-time communication protocols.

Many well-known technology companies—including **Cisco**, **Poly**, **Dialogic**, and **Logic,** have built commercial products using [reSIProcate ](https://github.com/resiprocate/resiprocate)as a foundational SIP signaling layer.

***

### Why This Architecture Matters

Because PortSIP PBX is **designed and implemented entirely in-house**, rather than derived from an open source PBX framework, we are not constrained by legacy architectures or design limitations common in community-driven PBX projects.

This approach allows PortSIP to:

* **Rapidly innovate** with modern Unified Communications and Contact Center features
* **Optimize performance at scale**, from SIP signaling to media handling
* **Design true multi-tenant and cloud-native capabilities** without architectural compromises
* **Deliver faster, more effective technical support**, backed directly by the engineers who built the system

***

### Trusted by Customers

This level of architectural control and engineering ownership is a key reason why customers and service providers trust PortSIP PBX for mission-critical, large-scale cloud PBX, UCaaS, CPaaS, and CCaaS deployments.

PortSIP combines the proven reliability of an industry-standard SIP stack with the flexibility, performance, and innovation of a **modern, fully proprietary PBX platform**.