Is the iPad Ready to Be a Dedicated Phone?
In the case of an emergency, your iPad will not replace a dedicated mobile phone. VoIP phones simply do not allow a 911 responder to have enough information about your location. If you really need help, grab your phonenot your VoIP app.
Another annoying occurrence is dropped calls. Dropped calls do happen on the iPad because of flaky Wi-Fi connections in the iPhone OS software running on the iPad. Apple has already said that it is aware of the problem and is working to fix it. Until the fix comes, you may want to get used to your data connection getting dropped every 10-15 minutes.
The bottom line is that your iPad should not be your dedicated phone line. The iPad can make calls, but there are still issues that need to be resolved such as maintaining a network connection. These will be resolved in time, but until then your iPad will make a great backup phone. Just don't hold it up to your ear when you make a call!