ISDN lines became generally accepted for two reasons as the standard for fixed line connections. First of all, you can use the telephone and internet at once. Secondly - and not insignificantly - it allows caller ID. This free application indicates who called and when on your computer. As soon as the telephone rings, the Freeware launches with details of the caller. Never get caught by surprise again - find out who's calling you and from where before you pick-up the phone.