Telephony disabled in Hub 4 router
I have Hub 4 router and it says Telephony disabled so headsets I've plugged into the hub don't work. How do I activate telephony in the Hub 4 router so headsets will work? All phones I've plugged into Tel 1 at back of router are dead - no dialling tone. What simple cheap phone could I buy to check it's not the headsets. Or does Telephone Disabled mean no headsets will work?