How we test cordless phones

There are a number of reasons why it’s essential to test cordless phones. It enables us to single out the easy-to-use landline handsets, models that have excellent sound quality, a long range and effective call-blocking technology.

We put home phones through a wide variety of tough lab tests, so you can buy with confidence and find the perfect one for you. And as well as finding the best, we’ll help you to avoid the phones that sound crackly and distorted, or have such short ranges that they won't work upstairs.

What makes a Best Buy cordless phone?

We put every phone through the same tests - a mixture of hands-on assessments by independent experts and technical lab testing - so we can answer the important questions with confidence, and give you a verdict you can trust.

These include:

• How clear are calls to and from the phone?
• How effectively can it block nuisance calls?
• How easy is it to use the phone and read the screen?
• What's the phone's range like?
• And, most importantly, should I buy it?

Head straight to our cordless phone reviews to compare results, or read on to find out more about how we test landline phones.

How clear are calls to and from the phone?

We make a series of calls from each phone while an expert panel checks the sound quality at both ends of the line. Our experts listen to calls on the speakerphone and assess the sound quality of incoming and outgoing messages left on the answering machine.

How effectively can it block nuisance calls?

Unwanted nuisance calls are sadly a fact of life, but not every phone is capable of stopping them. Which? members have frequently complained that their cordless phone doesn’t block the numbers it claims it can, so we test each model's capabilities by making calls from various types of phone numbers, to verify that the blocking is working as well as it should.

We check whether a handset can block the most common categories of spam calls, including:

• International numbers - not all phones can block calls from abroad, so we check to see if pesky offshore call-centres can be stopped in their tracks.
• Mobile numbers - with mobile phones so common now, it's important to ensure your landline can block even roving cold callers.
• Withheld numbers - a large majority of spam callers try to hide their identity, perhaps by dialling 141 before a number, which is why it's helpful to block these kinds of calls.
• Unavailable numbers - another tactic of unsolicited callers is to mask the caller ID entirely, even from the telephone exchange, so you won't know who is at the other end of the line until you pick it up.

How easy is the phone to use?

Ergonomic experts assess how easy it is to set up the phone, add contacts to the phone book and make and receive calls. We rate the general handling, including whether the buttons are well spaced so pressing the right numbers is simple, and whether the names and numbers on the display are easy to read. We also check the maximum volume of the default ringtone from the base station and the handset, so you can make sure you never miss a call.

What's the phone's range like?

Our test finds out at exactly what distance the signal drops, so you can work out whether the phone will work in every room in your house. We also note whether the phone will warn the user if the signal is getting too weak before cutting off.

How reliable is the brand?

As well as testing cordless phones in our lab, we also survey thousands of Which? members to find out which brands are built to last. If our survey reveals that a brand is unreliable, we won't permit any of its phones to be Best Buys, no matter how well they do in our lab assessment.

This unique cordless phones reliability survey means that you can buy with confidence, knowing that your new phone is unlikely to let you down.

Should I buy it?

We give every home phone we test a Which? test score out of 100 so you can see which are the best and worst and can directly compare between models.

Each of the assessments described above goes part way to making up this test score, although certain assessments are more important than others and so get a heavier weighting in our evaluation. We think the most important job of a phone is to make and receive clear calls, so a large proportion of our test score is based on this. 

The score is broken down as follows:

• Sound quality 40%
• Call blocking 20%
• Ease of use 15%
• Signal coverage 15%
• Features 10%

A phone needs to score 77% in our tests to earn our cordless phone Best Buy recommendation, or if it scores 45% or below it's a cordless phone Don't Buy.