Maryannne - May I ask for specific answers to a couple of questions that we are sliding over -

You definitely have u-voice? Not POTS with U-verse?

You mentioned a pulse/tone switch - does the phone have a pulse tone switch?

In fact what is the make/model of the phone?

You have tried the phone on a POTS line? Even if you have u-voice you should be able to answer and talk on your phone. The only problem would be dialing & ringing If the phone is in working order. I hate to have you spend any money on devices until you are sure the phone is functional.