Volume Controls

The ring volume on some phones can be adjusted to suit your home or office. If your corded phone is closely at hand, many people prefer to use a quiet setting to add a little serenity to your room. Some callers speak too loudly, so a handy feature is to be able to adjust the speaker volume via a handset volume control. 

SpeakerPhone

Many phones are supplied with a digital speakerphone built into the set's base. This allows third parties to also listen to the conversation, and also assists you by freeing your hands for other tasks and giving you greater flexibility. A good example is collaborating on a computer project with your caller. A speaker phone volume control is also a useful function to look for.

Caller ID

With caller identification (Caller ID), you can often screen incoming calls by being able to see the phone number of the caller displayed on the screen. As soon as someone calls you, their number (and sometimes their name) may be displayed on screen. Many numbers are hidden though - for example, some mobile numbers, some international numbers and some privacy protected numbers cannot be displayed, which limits the practical usefulness of Caller ID. 

Caller ID History

Some phones can store the last sequence of call numbers received by the set. A good phone might remember the last 100 or so numbers, for example. This is particularly useful for calls you may have missed. Possible handy options for this function include being able to call them back, add them to your phone book, add a few to your "Instant Call" list, or delete them.

Phone Book

There are popular phones available with the capability of storing 100 or more names and numbers in their phone books, or even thousands on special dedicated models. This is an important feature to consider because it can save you real time when calling friends and associates. In just a second or two you can find someone's number and click to initiate a call.

Redial

Redial is a useful feature in the event that the person you are trying to call is not currently answering. Instead of having to key in their number on subsequent attempts, you can simply press the Redial button. Most phones with Redial store the last number you have dialed in its memory. The Redial button then is used to conveniently dial the last number you have attempted, in the event that you think they may be available to talk soon. Some phones can be set to automatically redial multiple times.

Speed Dial

Some phones have one-touch capable memory keys for a small number of frequently called numbers. Some phone models have 3-20 time saving one-touch stations available for example. These are extremely useful and convenient for people you call daily, such as your partner, best friend or close business associate. Speed dial is a great option to look for if you have a contact you like to phone more than once a day.

Call Waiting

Call waiting is a feature that allows you to suspend the call you are currently on so that you can answer a second person's call. You are notified of a second incoming call by a tone or beep which you hear during your current call. Some phones allow you to cancel the warning tone prior to or during a call. You can choose to interrupt the first call to take the second one (usually via a flash button), or ignore the second caller. On some phones, the second caller is redirected to a voicemail service. You can switch between the two callers without too much difficulty. Or you can quickly end the first call, hang up, and take the second. Generally you will negotiate with one of the callers to call them back. Call waiting is most useful when Caller ID is also activated.

Caller On Hold

During a phone conversation, you may need to place the other person on hold. You may need to answer your mobile phone, or respond to a real human being in the room, or some other eventuality. After informing your caller, on some phones you are able to press a Hold button and the caller generally hears some music while you temporarily deal with the interruption. Press the button again to resume the call. This is a great feature if you make many calls each day or are using your corded phone for business reasons.

Mute

In this day and age where just about everyone has a mobile phone, a mute function on your corded phone is a useful option at certain times. For example, you might be talking on your mobile or to a real live human being when the desk phone rings and it is inconvenient to answer it, and you do not wish to be interrupted by the loud rings. This is sometimes called a "do not disturb" function.

LCD Display

A clear backlit LCD display is a very useful feature of a corded phone. Look for a model with big clear letters and numbers that are easily legible both in bright light and dark lighting conditions. Some models have an adjustable screen so you can change the angle to suit the level of your phone and its position on your desk or table. Besides standard info like phone numbers and available options, phones also display useful information such as the time and date. Talking about big letters and numbers, that principle also applies to the buttons on your phone. Look for nice big buttons so you can dial numbers quickly without fumbling.

Sound Quality

While the phone specs won't be able to clearly demonstrate the speaker and receiver quality provided by your corded phone, you will be more likely to be happy with the quality of your new phone if you purchase a model from a reputable brand. You may be able to find online reviews of the phone you are interested in, if the audio is poor, that is the first thing a poster will complain about.

Manual

Finally, a clear and well written manual is worth its weight in gold. You don't want to spend any more time than you need to in learning about the multiple functions of your new phone. Ideally you want to be able to just plug it in and begin using a few essential functions immediately and intuitively. Other useful but non-essential functions can wait until later. While you won't find the manual described in detail in the phone's specifications, buying a top brand phone increases the likelihood of also obtaining a well written manual.