I have been given and old EB-GD68 Panasonic Mobile phone. I have a Telstra sim card and inserted it into the phone and I can receive calls OK but I can not get the key guard to turn off. Please can you tell me how to disable the key gurad. The phone shows an image and the word Telstra but then replaces this word with a padlock next to a small icon of a mobile phone when I press teh call button so I think it must be a key guard. Thank you