Text messages ok, but I no longer use Viber for voice calls due to low quality
Voice quality has improved but very dependent on being close to a tower. Still drops out several times during long call. Sometimes won’t connect. Really is not worth the hassle. I’d rather pay $10/month and get an international calling plan. It’s just so frustrating to use when mobile!!!

Text messages ok, but I no longer use Viber for voice calls due to low quality