Please try the following: unplug the PhoneTray modem from the USB port, wait 10 seconds then plug it back in. After that open PhoneTray, go to the Settings - Lines screen by clicking Settings -> Lines on the left panel and then re-select your modem for Line 1 on the right panel:
PhoneTray should show modem status as Ready after a few seconds.
Also please check the phone line that goes to the modem. Unplug both ends then plug them back in to make sure the connection is secure. You can connect your phone to the jack marked as Phone on the USB modem and check for a dial tone. If you can hear a dial tone everything is connected properly.