Yup. Reliable ISP for Vonage is a must. However, they have a great backup system. If for any reason your ISP or power go down, you program your account to forward the call to any phone number you choose (like your cell). You miss nothing. I've been off the Bell 'grid' for 4 years now and am surviving just fine and saved a TON! Take a look at all the features that are free as well: http://www.vonage.com/features.php Vonage VoIP Internet Phone Features & Benefits One low price. Lots of great features. That's Vonage! Tired of paying extra for basic features like call waiting, caller ID, and call forwarding? Well, Vonage offers these features, and more than 25 other internet phone features at no extra cost! Plus, we offer the added convenience of managing your preferences for these features online! See how Vonage matches up against the competition. Included Features * Caller ID with Name * Call Waiting * Voicemail Plus® * Call Transfer * Enhanced Call Forwarding * 3-Way Calling * Caller ID Block * Call Return * Do Not Disturb * Anonymous Call Block * Repeat Dialing * International & Directory Assistance Block * Call Hunt * Ring Lists * Vonage Access * Bandwidth Saver® * Network Availability Number® * Click-2-Call® * Vonage Online Account * 211 Dialing * 311 Dialing * 411 Enhanced Dialing * 511 Traveler Information * 811 Dialing * 1-700-WEATHER * 1-700-GREETINGS