My daughter is currently living in Australia. I have an iphone4 with O2 in UK. She has an iphone4 with Vodaphone Australia. For the last six week-up until two days ago, we had successfully texting and calling each other with Viber. However, for the last two days it has not work. I feel like my right arm has been cut off. I have uninstalled and re-installed Viber. This had no effect. I can still Viber message my husband in the UK succesfully. Any ideas??????