HD Voice , which improves voice-calling clarity , is coming to more U.S. networks . Feature expands frequency range of sound transmitted by phones . When Apple unveiled the iPhone 5 in September , the company announced that the phone is equipped for HD Voice and that 20 carriers around the globe would have the ability to offer it . AT & T confirmed its plans to add HD Voice later this year . Comment:
HD Voice , which improves voice-calling clarity , is coming to more U.S. networks . Feature expands frequency range of sound transmitted by phones . AT & T confirmed its plans to add HD Voice later this year . Comment: