You should typically choose a cordless phone charger that is made by the manufacturer of your phone and is suggested for use with the particular phone you already have. Depending on the phone you have, however, you may be able to choose from a number of different types of reliable chargers that can offer you different features. You may also be able to find one from another company other than the one that made your phone, but you should be careful about using such products as they may potentially void the warranty on your phone and cause damage to components within the phone.
A cordless phone charger is a device into which a cordless phone can be placed to both hang up the phone and to charge a rechargeable battery within the phone. These chargers are often bases into which the phone can be placed, allowing the phone to stand upright while not in use. They may have lights that display when the phone is charging or when fully charged, as well as indicators to show when the phone is in use. In general, you should choose a cordless phone charger that is made by the manufacturer of your phone and that is designed to work with the phone model you have.
There are a number of different features that may be available with a cordless phone charger, so you should look for one that provides you with the options you want. If you only have one phone, or need a charger for a primary phone, then you may want to find a charger that also has an answering machine, caller ID, and a speaker phone built into it. On the other hand, if you are looking for a charger for secondary phones that are part of a single system, then you can often find simpler chargers that do not have such features. Many chargers will also allow you to find a misplaced phone by pressing a button to cause it to begin ringing.
You may be able to find a cordless phone charger made by a company other than the one that manufactured your phone, though you should be careful when doing so. Unless the charger you purchase is authorized or licensed for use with your phone, the use of it may potentially cause damage to your phone or the battery within it. The use of an unauthorized cordless phone charger with your phone may also void the warranty on your phone, so you could be responsible for any damage to the phone caused by the charger.