Here you can find info how to activate Viber on Windows Phone 7

1) disable proxy in WiFi on the device (if enabled)
2) open Internet Explorer on device and visit this page
3) you can install Viber from here (Viber v2.2.1.0) (you need Full Unlock first)
4) on your phone next you go here, installation of certificate will be prompted, agree with it
5) go to phone Wi-Fi settings and set proxy IP: Port: 80, there will be only Viber app working, internet disabled
6) run the app Viber, start to authorise using phone number, wait for SMS code, do not enter it to Viber
7) once SMS received, using your PC go here and enter code there
8) you got new 4 digits code from previous page and enter it into the Viber app and press next
6) once Viber asks your name, it means activation finished, now go to WiFi settings and disable proxy

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