Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
Check whether your phone line is properly connected, first of all. The phone line should be connected to the source of your phone service at the other end; at the HP device end, it should be into the jack labeled 'LINE' or 'L', not the jack labeled 'P' or 'PHONE' or labeled with a phone handset logo.
Check also as to whether you get a dial tone from that phone line... if not, your phone service may be 'down', and your phone service provider may need to be contacted, especially if you have landline or POTS (ordinary) phone service.
After that... well, Reply and tell me other details about the problem and its background. Esp., whether you changed phone service lately. And other possibly relevant facts. I'd like to offer more advice until a solution is reached, so feel welcome to Reply To Expert.