If you have access to edit your extensions, you will have a page that looks like the following:
Clicking on an extension name will allow you to edit the extension.
Note: Do not edit the extension named MASTER EXT. An incorrect update on this extension may disable the entire account.
After selecting an extension, you will see a page similar to the following.
NOTE: Do not edit the Extension number. This can break things.
Normally, you will only need to change the name, email, voicemail PIN, and Enhanced Services.
Enhanced Services
Clicking the Enhanced Services button will bring up the Enhanced Services panel.
Features can be enabled and disabled using the X and Checkmark icons in the middle of the panel. The Lock symbol will require a user to enter their Voicemail PIN in order to access the feature.
Change the options for the service using the Edit icon on the right. The most common service to change is the Directory to add speed dials to phones.
Directory
Click the Plus symbol on the top right of the page to add a new line.
Extension: The extension or phone number to dial.
Label: The name to assign to the number. By default, extensions will show their extension name.
BLF: Busy Lamp Field. For extensions, will show a status light on the phone for whether the person is available or not.
Depending on your model of phone, you may need to reboot the phone to see the changes.