If you have dial tone but you cannot call out or answer, the phone is probably messed up inside. The wiring inside the phone allows you to hear dialtone but is not connected correctly for letting you control it.

You can take it to another persons POTS and try it.

A pulse phone should work with POTS. Not sure about U-voice. Cannot find an answer on the web site. But, it should answer on u-voice, just not dial.

You originally said it was a dial phone - I assumed pulse. If it actually has a switch to do either tone or pulse, tone would be better. But, it would only affect outgoing dialing. It should answer on either.

Of course, when trying to figure out what is wrong, you have to try anything. If it works on pulse, but not tone the tone generator is fried. If it works on tone, you don't need pulse. If it works on neither (even answer) the internal wiring is really bad.

I believe you can buy these phones for less than $10/20. I think Target or Walmart is a good source. With caller ID, too.