Welcome to the Community!
How long has the feature not worked for you? Please check the settings to see if TV Call Display was put on snooze by accident. To cancel snooze please Go to channel 975, select Manage Snooze Settings and select Cancel Snooze. I would recommend you and @Pauly both to reboot the TV boxes as well.
Please keep us posted.
TV call display according to Rogers is NOT AVAILABLE in HAMILTON,CALEDONIA,YORK
TV Call Display Stopped Working
TV Call Display Stopped Working for us today on all of our cable boxes as well as other people we know with Rogers