I have recently purchase a Cisco ATA192 VoiP Telephone Adapter/SIP ATA w/ 2-FXS Ports to pair with my BT supplied Business Superhub2 (BT recommends this pairing) No success with pairing, and my PRT LED is Steady RED, if I press the PRT it changes to flashing RED and then reverts to Steady RED. No information available what this means - is the Cisco ATA192 fault?