Hailing from Yealink’s T4S series, the T42S is one rock-solid 12-line IP phone. This phone embodies all that the company is about.

There are good reasons why Yealink leads the SIP-phone market. For one, it is striking how user-friendly their phones are. A company that designs products based on ‘real-world necessities’ always deserves its props.

And the Yealink T42S knows its role too. It is easy to use, its performance is flawless, and it is compatible with other office devices.

But despite knowing its role, where would this role fit? There is no such thing as a ‘universal phone’. Different phones fit different needs. So, where does the T42S belong to?

We will guide you in finding that out. Towards the end, you should have a good idea of whether this phone will be a good fit for your office or not.

Originally released in 2017, the T42S is the improved version of the older T42G, just like how the entire T4S series updates on the preceding T4 series. The phones from both series look identical, but the T4S devices have all kinds of enhancements.

Except for the better overall performance, the T4S series also comes with unified firmware. This is like having multiple smartphones running with the same Android OS.

This makes management and provisioning easier.

There are other improvements to the T4S series. However, these will also become evident when reviewing the T42S specifically.


The T42S exhibits pure business elegance. The matte surface, the metallic buttons, the heavy headset. All these small but nice touches.

The phone is quite compact. The 2.7-inch LCD proves sufficient for displaying all the information. However, it can be a bit painful to the eyes at first.

Especially since most people are already adjusted to vivid desktops and smartphone screens.

Sound Performance

The T42S delivers excellent sound quality! We can attribute that to Yealink’s Optima HD audio system and the Opus codec.

This combination of software and hardware makes for one crisp and clear communication experience. Even when the network connection is not great, the phone behaves well.

In addition, all the T4S models are supplied with HAC (Hearing Aid Compatible) handsets. The HAC system aids people with hearing loss to hear the other side more clearly. We have not tested that feature, but we assume that it will be helpful to some.

Set-Up and Configuration

Setting up and configuring a single device is simple and easy. It is done through Yealink’s browser configuration page and takes minutes.

As for this unified hardware…All phones across Yealink’s range have the same interfaces and firmware. This makes it easy to navigate your way when setting up many devices.


The T42S comes with two Gigabit Ethernet ports. The first one can be used for connecting it to a PC. The second one is generally used for powering the device via PoE.

Powering VoIP devices via PoE is now the standard. However, the T42S can also be powered via a standard 5-volt AC adaptor. Remember that most retailers do not include it, so it must be purchased separately.

In addition, the T42S also has a headset port and EXT port for attaching expansion modules.

(If you attach expansion modules, you will need an extra AC power adaptor.)

A single USB 2.0 port can also be found. It can connect devices such as a Bluetooth headset or a WiFi dongle. Alternatively, a recording device can also be plugged in there.

Again, keep in mind that such accessories are purchased separately.

The T42S has a wall-mountable integrated back stand with 2 adjustable angles.

T42S backside ports

User Experience

The T42S comes with 6 programmable keys – 3 on each side. These can be used to achieve optimal workflow.

Most commonly, these so-called DSS keys are used for speed dialing. However, they can also be programmed to perform other functions.

There are also four soft keys at the bottom of the display. They are contextual buttons. This means that their labels will change and be relevant to whatever you’re doing at the time.

For example, if on a call, these buttons will display the essential call-handling tasks. The options for holding or transferring a call will be a click away.

Also, there’s an option to take a call while on a call. By clicking the ‘answer’ soft key while the second call is incoming, the T42 will automatically put the first one on hold.

I am similarly, starting a conference call while already on a call is also a one-click task.

The volume button at the bottom is also adaptable. When pressed during a call, the button adjusts the call volume. If pressed outside a call, it would adjust the ring volume.

These contextual keys are much taken for granted at this point but are still of incredible utility.

The same goes for the status bar at the top. A simple feature that will help users stay on top of things.

Overall, it is safe to say the T42S has all the call features expected from a business phone. The beauty of this – and all Yealink models – is in retaining the simplicity in doing so.

Regardless of previous experience, professionals should immediately get into this phone’s flow. It is just that user-friendly and intuitive.

Keep in Mind

The T42S is easy to use, but there are better alternatives for bigger offices.

The T42S comes with a total of 6 programmable keys. Six keys should do just fine in smaller offices. But as the office increases, so does the need for impeccable workflow. And users might need more DSS keys to achieve that.

So, why put oneself in a corner? Better consider IP phones with at least 10 DSS keys for bigger offices. More programmable keys enable your office to make use of more PBX features. Which in turn creates one smoother collaboration experience.

Surely, it will be a bit more costly. But your teams will be pleased in the long term.

In conclusion

The Yalink T42S is another example of Yealink’s product consistency. On the one hand, all their devices support identical features and interfaces.

On the other, all of their phones feel solid and reliable.

With this particular model, Yealink has managed to pack its signature features into one smaller and cheaper device.

The balance of price point and feature set make it a great entry-level IP phone.

The only shortcoming is the shortage of DSS keys. But this is from the perspective of bigger offices.

From the perspective of smaller offices, this is only better. Here’s a nice compact phone packed with everything the average business user might need.

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