What Is Firmware, and Why Update It on Phones and Adapters?

What firmware actually is

Every smart electronic device runs software. On a computer it is called an "operating system," and you install programs on top of it. In small, dedicated devices, such as an IP phone, an adapter, a router or a switch, this software is called firmware.

The name comes from the English word "firm," meaning stable: it is software that sits "permanently" inside the device, and is not something the user installs and removes. It determines how the screen looks, how the keys respond, how the phone talks to the PBX and what menus there are.

When the device starts up, the firmware is the first thing that runs. Without it, the phone is a plastic box with a dark screen.

Firmware versus settings: two different things

It is important to tell firmware and settings apart. The firmware is the software itself, the same software in all phones of the same model and version. The settings are what makes your phone unique: which PBX it connects to, which extension it is, what appears on each key, and what language the menu is in.

A simple analogy: the firmware is the operating system of a mobile phone, and the settings are the contacts, ringtone and wallpaper you chose. Updating the operating system is not supposed to delete your contacts, and in the same way, a regular firmware update is not supposed to delete the phone's settings.

A factory reset, on the other hand, deletes the settings and leaves the firmware. These are two different actions, and it is best not to confuse them.

Inside the device too, they are stored separately: the firmware in one area of memory, and the settings in another. This is why one can be replaced without touching the other, and why a phone that was reset can get its settings back through auto-provisioning.

Why update at all

Fixing faults. No software comes out perfect. A phone that disconnects now and then, a key that does not respond, a Hebrew menu that displays backwards, or echo on the speakerphone: sometimes the cause is a bug in the firmware, and the manufacturer releases a version that fixes it.

Security. From time to time, weaknesses are discovered in devices that allow unauthorized access to the management interface or to the extension account. Manufacturers release updates that close them. A device that has not been updated for years is more exposed, especially if its management interface is open to the network.

Compatibility. PBXs, browsers and security standards move forward. A device with very old firmware may stop connecting properly, for example when the server requires an encrypted connection of a newer version.

New features. Sometimes an update adds a capability: support for new headsets, an improvement in Hebrew, or a feature on the keys. That is nice, but it is usually the least urgent reason to update.

The risks of updating

A power outage in the middle. While the firmware is being written to memory, the device is vulnerable. Cutting the power or the network cable in the middle can leave it in a state where it will not start. Most newer devices can recover, but not all.

A change in behavior. A new version can change a menu, move a key or change a default. Employees are used to one thing, and suddenly it is different.

A new bug. Sometimes a new version fixes one problem and creates another. This happens even with large manufacturers.

Hard to go back. On some devices it is not possible to return to an older version after an update, or it takes work. This is why you do not update "just to try."

There is also a "quiet" risk: an update that was not tested against your specific PBX. A version that works perfectly for thousands of other customers may behave differently with your settings, for example with BLF keys or a particular codec. This is why testing on one device is not a waste of time, but part of the update.

Who does the update

At home, people update their mobile phones themselves. In an office with twenty phones, it is less simple. If every employee presses "update" whenever they feel like it, the office will have five different versions, and every fault will be a mystery.

This is why, in an organization, a firmware update is usually the job of whoever is responsible for the equipment: the IT person, the technician or the PBX provider. They test the new version on one device, make sure everything works against the PBX, and only then update the rest.

The regular user has one important role: if the phone shows a message that it is updating, do not unplug it. Wait a few minutes until it starts again.

In a small office with no IT person, the simple way is to set a rule: do not press "update" on the phone, and if a message about a new version appears, tell the equipment provider. It takes a minute, and saves a morning without phones.

Automatic update through auto-provisioning

Phones managed with auto-provisioning download their settings from a server every time they start, or on a schedule. The same mechanism can also tell them which firmware version to install.

The advantage is clear: whoever manages the equipment sets one version, and all phones of the same model reach it on their own, without anyone going from desk to desk. You can also schedule the update for the night hours, when no one is talking.

The disadvantage: if the chosen version is problematic, all the phones receive it together. This is why you test on one device first, and only then roll it out to everyone.

Some devices can also check on their own whether the manufacturer has a new version and install it. In an office, it is usually better to keep this turned off, so that the update happens in a controlled way and not as a surprise.

What an update looks like from the employee's side

On most phones, an update looks like this: a message such as "Updating" appears on the screen, sometimes with a progress bar. The phone stops receiving calls, restarts once or twice, and returns to work after a few minutes.

During this time you do not touch it: do not cut the power, do not pull out the network cable and do not press any keys. If the phone gets power through PoE, do not switch off the switch in the cabinet either.

If after a quarter of an hour the phone is still stuck on the same screen, that is the time to contact support. It is not recommended to try to "rescue" it yourself with a reset, because that may make things worse.

Versions: how to read a version number

Every firmware has a version number, for example something like 1.2.3.4. Each manufacturer numbers differently, but usually the first part identifies the model or series, and the last parts go up with each new version.

When you contact support with a fault, it is worth stating both the model and the firmware version. It saves questions.

When not to rush to update

If everything works, and the update does not close a security problem and does not fix a fault you have, there is no reason to rush. Wait a few weeks, see that the version is stable, and update at a quiet time.

Do not update before an important event: before a fundraising night, a donation day, or the eve of a holiday when the office is busy. And never update all the phones at once during working hours.

A good check after an update includes a few test calls: an incoming and outgoing call, a transfer to another extension, pressing a BLF key and listening to the voicemail box. If everything works on one phone, continue to the others.

End of support: when the updates run out

At some point every manufacturer stops releasing updates for an old model. This situation is called end of support (End of Life, or EOL). The phone keeps working, but new faults will not be fixed, and security weaknesses that are discovered will stay open.

This does not mean you need to throw the phone away the next day. But it is a sign to plan a replacement in the coming years, especially if the device is exposed to the network or serves an important workstation. When budgeting for an office, it is worth knowing which devices have already reached this stage.

Not just phones: router, switch and adapter

The router, the switch, the firewall and adapters also have firmware. In the router especially, which stands between your network and the internet, security updates are particularly important.

On the other hand, a firmware update on a router can change settings that affect calls. Sometimes after an update a feature like SIP ALG, which we turned off on purpose, starts working again, and suddenly calls are cut off or there is no sound in one direction. After a router update, it is worth checking that the settings that matter for calls stayed as they were.

The same is true for a PoE switch: updating it briefly cuts the power to all the phones connected to it. This is why you update a switch only outside working hours, and tell the employees who remain in the office in advance.

An example from the field

In the office of a small moving company (a fictional name: "Ariel Moving"), one employee saw a message on the phone about a new version and pressed "update." In the middle of the update he unplugged the phone from the outlet, because he thought it was "stuck." The phone never started again, and the office was left without the secretary's line on a busy morning.

Since then, the office has set two simple rules: updates are done only by whoever is responsible for the equipment, and in the evening hours; and if a phone shows "Updating," nobody touches it. The fault has not happened again.