3CX PBX · Unified Communications & PBX

3CX SBC (Session Border Controller)

Name: 3CX SBC (Session Border Controller) — 3CX PBX
Brand: 3CX PBX
Availability: InStock

Free SBC for connecting branch and remote-office SIP devices to a central 3CX PBX.

Quick answer

3CX SBC is a free component for securely connecting SIP phones at branch or remote offices back to the central 3CX PBX — handling NAT traversal, encryption and auto-provisioning.

3CX SBC is a free component that runs on inexpensive hardware (Raspberry Pi 4+, Intel NUC or any small Linux box) and brings the SIP phones at a branch or remote office back to the central 3CX PBX through a single, TLS-encrypted tunnel. It solves the classic SIP-over-NAT problem and removes the need for per-phone manual configuration.

Key features

What it offers

Runs on a Raspberry Pi 4+ or mini-PC
Connects branch SIP phones to the central 3CX
TLS-encrypted SIP signaling + SRTP media
Auto-provisioning of branch phones from central console
Dual-internet failover option

Tech Summary

Important technical data

Hardware: Raspberry Pi 4+ or mini-PC
Capacity: 5–30 phones on Raspberry Pi; more on mini-PC
Encryption: TLS for SIP + SRTP for media
Licensing: Free

Use Cases

When would you choose this product?

Multi-branch retail

Retail chain

An SBC at every store, central PBX in head office.

Banking

Bank branches

SBC at each branch with IP phones for tellers and managers.

Hospitality

Hotel chain

SBC at each property with guest-room phones and front-desk.

Who is it for?

Multi-site organizations centralizing on a single 3CX PBX.

Frequently Asked Questions

Frequently asked questions

Is it really free?

Yes — the 3CX SBC software is free. You pay only for the small hardware (Raspberry Pi or mini-PC).

Is a Raspberry Pi enough?

A Pi 4+ handles 5–30 IP phones comfortably. For larger branches use a mini-PC or small Linux server.

What is NAT traversal?

Branch SIP phones sit behind the branch router's NAT; without an SBC, registering them to the central PBX is painful. The SBC tunnels them through cleanly.

Is TLS encryption used?

Yes — TLS for SIP signaling and SRTP for media are the default.

Can it failover between two internet links?

Yes — if the branch has two internet connections, the SBC can failover between them.

How are branch phones provisioned?

Configuration is pushed from the central 3CX admin console; phones at the branch auto-provision through the SBC.

Vendor's official product page

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3CX PBX — 3CX SBC (Session Border Controller) →

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