Just got my MJ and I get a dial tone but can't make calls using either the phone or the softphone. The softphone consistently displays the message "Please Connect to the Internet, and double click [error 3]" after which MJ restarts, with the same result.
I've:
unplugged and restarted MJ many times
run magicfix and the upgrades multiple times
got all my security turned off
had my ISP open some ports that MJ tech support said to (can't seem to get in touch with them right now)
bipassed my router
How does your router connect to the Internet? I suspect that there is another router between you and Comcast. Log into your router and check its WAN IP address. If it begins with 10, 192.168, or 172.[16-31], another router is present that may be causing your problem.