Ok if I’ understanding well no problem from IP calls to TDM calls (seems a local network , it ‘right?) , so please do you have more information’s about the external connections , (what kind of router/firewall ???) ,I’ agree with BacherJr ,but before call Samsung for a replacement , we need more information. 99 % of the problems is the network issues . We are ready to help , just y’need more information .