Your description is rather lacking in detail! So without really understanding your problem here's something that might help: Worldwide telephones have plugs/sockets have 4 wires and BT, in it's wisdom, use a combination unique to the UK. So as your equipment is almost certainly designed for everywhere but the UK the lead from the VoIP box to the BT socket will be trying to connect to the wrong pair of wires. If you've bought and adaptor to solve this problem then you should be getting the dial tone. Generally if you have a lead with a BT plug at one end and a standard international plug at the other then this will swop the inside/outside pair round for you. If you add an adaptor to this all you are doing is change it back to a standard BT cable.