3CX branch connectivity

Connect branch desk phones with the 3CX SBC over a single port, no VPN

The 3CX SBC is a small, free app installed at a branch that securely tunnels multiple remote IP desk phones back to your central 3CX over a single port, auto-provisioning them and solving NAT with no per-phone port-forwarding and no VPN.

ECOLOR sizes one SBC per branch, picks the right host hardware, secures the tunnel, and designs multi-branch 3CX topologies where head office hosts 3CX and each Saudi branch connects via SBC.

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MENA 3CX Solution Provider
SBC free on every 3CX edition
Saudi-based support

What is a 3CX SBC?

A 3CX SBC is a small, free software app you install at a branch or remote site that securely tunnels multiple remote IP desk phones back to a central 3CX over a single port, auto-provisioning them and solving NAT with no per-phone port-forwarding and no VPN.

It runs on Windows, Linux or a Raspberry Pi. You deploy one SBC per remote LAN, and many desk phones can sit behind it. The SBC opens a single encrypted 3CX tunnel between the branch and the central system, so branch phones behave as if they were on the head-office network.

It is important to understand what the 3CX SBC is not: it is not a firewall, and it is not a session border controller in the telecom-carrier sense. It is a 3CX tunnel and provisioning proxy. It is also only for physical IP desk phones — desktop, mobile and web-client apps do not need an SBC, because they connect directly from anywhere.

In practice, the SBC solves a very specific branch problem: getting several IP desk phones on a remote LAN to register cleanly to a 3CX that lives somewhere else, without exposing each phone to the internet or building a VPN. Instead of forwarding SIP and RTP ports for every handset, you run one small app at the branch, point it at your central 3CX, and it backhauls all the phones through a single encrypted tunnel — which also sidesteps the NAT and one-way-audio issues that plague direct remote-phone registration.

One port only: a single 3CX tunnel instead of port-forwarding every phone
Auto-provisioning: phones receive their configuration from the central 3CX through the tunnel
One SBC per branch LAN, with many desk phones behind it
Requires the central 3CX to be reachable via a public FQDN and the 3CX tunnel port

Why deploy a 3CX SBC at a branch

Single-port tunnel

All branch phones traverse one encrypted 3CX tunnel, so you never open a separate firewall port for each phone.

Auto-provisioning

The central 3CX provisions branch phone settings automatically through the tunnel — no manual per-phone configuration on site.

NAT traversal

The SBC solves NAT for the branch, so IP phones work behind the router with no complex port-forwarding and no VPN.

Many phones per site

A single SBC serves multiple desk phones on the same branch LAN, backhauling them together to head office.

Desk phones, not apps

The SBC is specifically for physical desk phones; 3CX mobile, desktop and web apps connect directly, without an SBC.

Central management

All branch phones are managed from the central 3CX at head office as part of one unified system.

SBC vs direct app connection

Scenario	Best option	Why
Branch with desk phones	3CX SBC	One SBC tunnels many desk phones with auto-provisioning and NAT traversal, no VPN.
Remote staff on laptops/mobiles	Apps (no SBC)	3CX desktop, mobile and web apps connect directly to the central 3CX from anywhere.
A single desk phone at a remote site	Often no SBC	One phone can register directly if the central 3CX allows it; add an SBC once several phones are involved.
Large branch with dozens of desk phones	3CX SBC	One SBC provisions and secures all the phones centrally instead of configuring each phone individually.

Rule of thumb: desk phones at a branch → SBC; users on apps → direct connection, no SBC.

How ECOLOR deploys a 3CX SBC

Assess the branch
We count the desk phones and their type, review the branch internet and firewall, and confirm whether an SBC is the right fit versus apps.
Provision the SBC host
We select a small host — a mini-PC, a Raspberry Pi, or an existing Windows/Linux server — and install the free SBC app at the branch.
Connect to central 3CX
We connect the SBC to the central 3CX using its public FQDN and the 3CX tunnel port, and confirm the encrypted tunnel comes up cleanly and stays stable.
Provision the desk phones
We add the phones on the central 3CX and let them auto-provision through the tunnel, so each phone receives its configuration with no manual on-site setup.
Test & harden
We test two-way calling and audio, harden the SBC host and the branch firewall, and document the topology for your team.

How the SBC tunnel works

Branch IP phones3CX SBC at the branchSingle encrypted tunnelCentral 3CX at head office

What you need

Central 3CX with a public FQDN
The 3CX tunnel port open and reachable to the central 3CX
A small host at each branch (mini-PC, Raspberry Pi, or an existing Windows/Linux server)
Supported IP desk phones on the branch LAN
A stable internet connection at the branch

The SBC itself is free on every 3CX edition — the only cost is the small host that runs it at each branch.

Saudi deployment notes & limits

The 3CX SBC is for desk phones, not a firewall replacement. It does not secure the branch network on its own; its job is to backhaul phone traffic securely to the central 3CX, while firewalling remains a separate responsibility.

The rule is one SBC per branch LAN, sized to the number of phones and the capacity of the host. On larger branches we make sure the chosen mini-PC or Raspberry Pi comfortably handles the expected phone count.

When a site is mostly mobile users or laptops, apps are simpler and cheaper than an SBC because they connect directly. Across Saudi multi-branch designs we typically host 3CX at head office and connect each branch with either an SBC (desk phones) or apps (softphones), chosen per site.

A few operational realities shape our Saudi designs. The SBC depends entirely on the branch link to the central 3CX, so a branch with a single unreliable internet circuit is a real risk — if that link drops, the branch phones go silent until it returns, and the SBC does not provide local survivability on its own. Where a branch must keep dialling during an outage, we discuss a second internet path or per-site failover rather than assuming the SBC covers it. We also keep the central 3CX FQDN and tunnel port stable and documented, because every branch SBC depends on reaching them; and we right-size the host so a busy branch is never bottlenecked by an underpowered Raspberry Pi. These are exactly the decisions ECOLOR makes with you before rollout, so the topology is predictable rather than improvised.

Frequently asked questions

Does the 3CX SBC replace a firewall?

No. The SBC is not a firewall and does not replace one. It is a 3CX tunnel and provisioning proxy that carries desk-phone traffic securely to the central 3CX, while your firewall still protects the branch network.

Do remote laptop/mobile users need an SBC?

No, apps connect directly. The 3CX desktop, mobile and web-client apps register to the central 3CX from anywhere without an SBC. The SBC is only for physical desk phones at a branch.

How many phones can one SBC support?

Many desk phones on the same branch LAN can sit behind a single SBC; the practical number depends on the host hardware. ECOLOR sizes the SBC to the expected phone count at each branch.

Does it need a public IP at the branch?

No. The branch does not need a public IP — the SBC opens an outbound tunnel to the central 3CX. What must be public is the central 3CX, reachable via its FQDN and the 3CX tunnel port.

Is the 3CX SBC free?

Yes. The SBC app is free and works on every 3CX edition. The only cost is the small host — such as a mini-PC or Raspberry Pi — that runs it at the branch.

Can one branch have multiple SBCs?

The rule is one SBC per branch LAN. Separate branches or separate LANs each get their own SBC, all connecting back to the same central 3CX at head office.

What happens if the branch internet drops?

The SBC needs connectivity to the central 3CX. If the branch internet drops, the tunnel goes down and the branch phones stop working until it recovers, so we recommend a stable link and discuss availability options where needed.

Deploy 3CX branch connectivity with ECOLOR

Whether you have one branch or a network of sites across Saudi Arabia, ECOLOR designs the right 3CX topology for you: 3CX at head office, branch desk phones connected via SBC, and mobile users on apps — including sizing, hardware selection and tunnel hardening.