# Pound Sign not showing on my Phone Screen Connected to Xfinity Modem ?

My cordless phone is connected to modem XB7, when I press # key on my cordless phone or desktop phone

the screen shows upside down letter " a " on phone screen instead of # ?    how can I fix it to show # on phone screen when I tap the # key ?

Could this be a Modem problem?

Because this doesn't work, I also cannot verify info when they tell me to tap # to contnue.

Thanks for any help with this...