Ive just set up 3cx v10 on my machine, it registers outbound sip providers ok but ignores the requests from my ip phones to register, the 2 phones im using are a siemens 470ip and a cisco 7940. Im using wireshark and i can see the register requests come to my machine but 3cx server just ignores the requests. In my frustration i set up Axon PBX with identical extension details and I have no problems with the phones registering with Axon pbx on the same machine. (yes, i make sure both Axon and 3CX do run at the same time); Both phone also register with external providers fine. Any ideas?