A method of communicating between a phone line network which includes a plurality of devices coupled by a shared phone line medium, and a remote network. The collar comprises a loop of flexible sheet material which extends, in use, around and engages the outer surface of a cup. Matrices A, B, G and the integers n and r are then published as the public key and matrix C is then kept as the private key. When an actuation assembly moves the contacts to the open or closed position, the contacts move longitudinally relative to the contact carrier.