[Note to Apollo!: If you can let us know what the problem is with the highlighting (sample page that is broken, etc.), we will be happy to fix it. The "Need help with this add-on?" link will do the trick. Thanks]
This addon highlights phone numbers on websites, and lets you easily find out where the phone number is located. Whenever you go to a website, it will automatically detect phone numbers on the site (in almost all commonly used formats), and highlight them (by default, it will underline them with a red dotted line -- but you can change that).
To find out where the phone number is located, you just hover the mouse over the phone number, and in 1/4 second (by default) it will start a lookup of the location of the phone number. As soon as the data is retrieved (typically less than 1/2 second), it will be displayed in an info box by the phone number. The box will automatically disappear when you move the mouse outside of the phone number or info box. You can get full details on the phone number by clicking on the location in the info box.
The addon uses (with permission) the database at wherecall.com.
There are currently two options that you can set. One is the number of milliseconds to wait before displaying the info box (by default, 250ms, or 1/4 second). If you find that the box is popping up too often when you do not want it to, you can increase this number. Or, if you want to get the phone number locations as quickly as possible, you can lower it. The other option is the highlighting style of the phone numbers. If you are familiar with CSS styles, you should be able to edit it to your liking (but be careful -- changing this could cause unwanted problems).