If your 3CX phone system runs in the cloud and you have a branch, store or second office with more than a few phones, you will probably need a session border controller (SBC) at that site. Until now, that usually meant setting up a Raspberry Pi or a spare Windows PC. The Fanvil A710 puts the same job into a small, wall-mounted box that you can manage from the 3CX console, with room for up to 100 phones and 50 calls at once.
Here is what it does, where it fits and what to check before you order one.
What is a 3CX SBC?
A 3CX SBC (session border controller) is a small service that sits on a remote site’s network and connects the phones there to a 3CX system hosted somewhere else, usually in the cloud. A 3CX SBC carries calls through one secure tunnel, so you don’t need to open lots of firewall ports or configure each phone separately.
Without an SBC, phones at a branch have to reach the 3CX server through the site’s router and firewall on their own. That is where the classic VoIP headaches come from: one-way audio, phones dropping their registration and calls that ring but will not connect.
The SBC fixes that by acting as a single point of contact. Phones talk to the SBC on the local network, and the SBC talks to 3CX. It also lets you provision new phones at the branch straight from the 3CX phone system admin console, which saves a lot of time when setting up a new site.
Router phone or SBC: Which does your site need?
3CX offers two ways to connect a remote site. A router phone is an IP phone with an SBC built into its firmware, which connects the other phones on that network. A dedicated SBC is a separate device or software service. 3CX suggests a router phone for sites with fewer than 10 phones and a dedicated SBC above that.
Tip: Router phones have one catch. They need a wired network connection to act as the SBC for a site, so a router phone running on Wi-Fi will not do the job.
Until recently, a dedicated SBC meant installing 3CX’s free SBC software on one of three platforms: a Raspberry Pi 5, a Windows 10 or Windows Server 2016 (or later) machine, or a Debian Linux box. All of these work, but each one is a small computer someone has to set up, patch and keep running.
What is the Fanvil A710?
The Fanvil A710 is a hardware session border controller built specifically for 3CX. The A710 connects up to 100 phones and other 3CX-compatible devices at a remote site to a cloud-hosted 3CX system, handles up to 50 simultaneous calls, and runs on Power over Ethernet at around one watt. It suits branch offices, chain stores and multi-site businesses.
In plain terms, it is a dedicated SBC that looks and behaves like any other Fanvil device on your network. It mounts on a wall, powers itself from a PoE switch (or a small 5V adapter), and shows up in the 3CX console alongside your phones.
A few details from the datasheet are worth pointing out:
- Security built in. TLS for call signalling, SRTP for encrypted audio, and AES128 and AES256 encryption, along with 802.1x network access control and VLAN support.
- VPN support. L2TP and OpenVPN, if your network setup needs it.
- Low power, no moving parts. Power draw sits around 0.75W to 1.14W on PoE. There is no fan, hard drive or SD card to wear out.
- PC pass-through port. The second Ethernet port is bridged, so it does not take away a network point.
How does the A710 compare with the other options?
| Router phone | Software SBC (Raspberry Pi, Windows or Debian) | Fanvil A710 | |
| Typical site size | Fewer than 10 phones, per 3CX guidance | More than 10 phones, capacity depends on the hardware | Up to 100 devices and 50 concurrent calls |
| Hardware | One of your desk phones | A Pi, PC or server you supply | Dedicated wall-mounted appliance |
| Ongoing upkeep | Low | Operating system updates, SD card or disk health, a machine left running 24/7 | Managed like a phone, through 3CX provisioning |
| Power | Shared with the phone | A few watts (Pi) up to a full PC | Around 1W on PoE |
| Watch out for | Must stay wired, and the site depends on one handset | More moving parts to troubleshoot | Currently needs a custom 3CX template from Fanvil |
The software SBC is still a perfectly good option, especially if you already have a reliable server at the site. Where the A710 earns its place is in the in-between: the site that has outgrown a router phone but does not have, or want, a computer dedicated to running the SBC.
It also helps when you are rolling out the same setup across many sites. A chain of 15 stores is much easier to support when every store has the same small box, rather than a mix of Pis and old PCs.
Where the A710 fits best
- Branch offices. A regional office with 15 to 40 staff gets the same 3CX features as head office, without a local phone system or a computer to maintain.
- Retail and franchise chains. Each store gets a few desk phones, a cordless system and maybe a paging speaker, all connected through one A710. New stores can be set up from the same template.
- Clinics, schools and multi-site practices. The A710 counts endpoints rather than just handsets, so intercoms, door phones and SIP speakers from the Fanvil range can sit behind it, too, provided they are supported by 3CX.
For staff working from home, a dedicated SBC is usually more than they need. The 3CX remote working apps or a single router phone tend to be the simpler option for a home office.
How setup works
The A710 is provisioned in 3CX much like a router phone. Based on Fanvil’s user guide, the process looks like this:
- In the 3CX admin console, add an extension, select the A710 as the phone model and enter its MAC address.
- Choose the option to connect it directly, so it acts as its own router device.
- Reboot the A710. It provisions itself and appears in the 3CX console, where you can check its status.
- Plug in the phones at the site. They show up in 3CX as plug-and-play devices, ready to be assigned to extensions and connected through the A710.
There is one thing to plan for. At the time of writing, Fanvil’s guide notes that the A710 uses a custom 3CX template, which installers need to request from Fanvil. This is part of what Com2 handles during setup, so it is not something your team needs to chase.
What to check before you order
Your internet upload speed
Each call uses roughly 100 kbps in each direction on the common G.711 codec. A site running all 50 calls at once would need around 5 Mbps of upload and download set aside just for voice. Most branch sites will never hit 50 calls at once, but upload speed is often the weak spot on standard NBN plans, so it is worth checking against your busiest hour. Quality of Service (QoS) on the site router helps keep voice ahead of video meetings and cloud backups.
Your phones and devices
The A710 connects 3CX-compatible endpoints. Many current Fanvil handsets are supported, but check older phones, cordless bases and intercoms against 3CX’s supported device list before you plan to reuse them.
Your network layout
Plan for the A710 to have a fixed address on the local network (a DHCP reservation works well), a PoE switch port or power point nearby, and phones on the same network or VLAN. Its ports run at 10/100 Mbps, which is plenty for voice traffic.
Is the A710 right for your sites?
If you run 3CX in the cloud and have a site with more than 10 phones, the A710 is worth a close look. It does the job of a 3CX SBC without a computer to look after, and it scales comfortably for most branches and stores. If a site only has a few phones, a router phone may still be the simpler choice.
A good next step is to list each of your sites with its phone count and busiest-hour call volume. From there, Com2’s 3CX engineers can suggest the right mix of A710s, router phones and 3CX SIP trunks for your business, and look after the setup.