Will the voice signal bandwidth and quality be improved if we get UFO to our door?

        This question is for the benefit of a person with hearing loss who really struggles to understand voice on the landline phone. One aspect is the receiver but she can have the signal routed directly to her hearing aids but the bandwidth is already restricted. We have the opportunity to have UFO provided and wondered if it would make any difference to the sound quality. Traditionally sound bandwidth is reduced (some high and low frequencies are cut out). Presumably with fibre this will not be necessary. Also modulation with fibre is different? However the sound quality would be affected also by the connection to the other party which would stll use the copper wire. Hence presumably the signal would be already degraded coming into the exchange? Same presumably applies even if we use a mobile phone? What will happen when all phone communication goes digital, will the full voice bandwidth be available?