Hi I purchased Gigaset C530 phones for myself and family. One son in Wellington and myself in Christchurch can talk Gigaset to Gigaset with no problems. The other son in Perth has set his phone up and cannot make or receive Voip calls at all. He can access the echo service and gets an echo but when calling either of the other phones, we get a ring but no voice. He has checked all his connections and has also spoken to Gigaset Australia and they went through the connections with him as well.  He can make calls via landline.  He recently upgraded his router / modem. can anyone offer any suggestions?